Starting with a surge of panic and violence as the hostage takers make their assault and subdue hostages, the hostage crises take to the stand-off phase which can last hours, days or months. The demands have probably been recieved by the negotiation making law-enforcement officials by now. The termination of the situation could be in peace or utter violence, leaving the hostages mentally perturbed for their lifetimes in either case.
The list here looks at 10 deadliest hostage situations in the history so far.

10 Baghdad Church Attack

Image: Baghdad Church Attack
The Baghdad church attack was an attack on the Our Lady of Salvation Syriac Catholic cathedral of Baghdad, Iraq. It occurred during Sunday evening Mass on 31 October 2010. The attack left 58 dead, with more than 100 taken hostage. 19 of the hostages managed to escape before Iraqi Rescue Forces stormed the church. Backed by American aerial support, the 4-hour siege resulted in the death of 41 hostages.
The al-Qaeda-linked Sunni insurgent group the Islamic State of Iraq claimed responsibility for the attack.

9 The Munich Olympic Tragedy

Image: The Munich Olympic Tragedy
This hostage situation famously known as Munich massacre was perpetrated by the Palestinian group Black September during the 1972 Summer Olympics in Munich, West Germany, on Israeli Olympic team members,11 in number, who were taken hostage and eventually killed, along with a German police officer. Soon after the crisis began, the hostage takers demanded the release of the 234 prisoners jailed in Israel and the German-held founders of the Red Army Faction.
Eight of the terrorist’s members were killed during the failed rescue attempt with three surviving assassins captured. Israel retaliated with ‘Operation Spring of Youth’ and ‘Operation Wrath of God,’ where they tracked down and killed all the Palestinians who were suspected to be involved in the massacre.

8 The Ma’alot Massacre

Image: The Ma’alot Massacre
This two-day hostage-taking situation involved 115 people, 105 of which were children. It took place on May 15, 1974 when three armed Palestinian radicals of the Democratic Front for the Liberation of Palestine entered Israel from Lebanon and made hostage of the teenagers on a field trip spending night in Ma’alot. The hostage-takers demanded the release of 23 Palestinian militants from Israeli prisons threatening to kill students otherwise. When after two days , the rescuing Golani Brigade stormed the building , the hostage-takers killed the hostages with grenades and modern weapons culminating in the death of 28 hostages, including 22 children.

7 Iran Hostage Crisis

Image: Iran Hostage Crisis
This diplomatic crisis between the countries of Iran and the United States escalated when a group of Islamic students invaded the American embassy in support of the Iranian revolution on November 4, 1979, just a few moments after Ronald Reagan had been sworn in as the new US president. 52 American diplomats and citizens were held hostage.
The failure of a  number of negotiations for release became conducive to the US military's rescue operation called ‘Operation Eagle Claw’ on April 24, 1980. This however resulted in an aborted mission, crash of two aircrafts, and the death of 8 American servicemen and an Iranian civilian.
Iranian students held a press conference during the Hostage Crisis, in a room decorated with anti-American slogans and propaganda against the former Iranian Shah.
The crisis ended on January 20, 1981 after the 52 American hostages were released by Iran into U.S. custody, having spent 444 days in captivity.

6 The Lebanon Hostage Crisis

Image: The Lebanon Hostage Crisis
This systematic series of abductions in Lebanon involved abduction of 96 foreign nationals between 1982 and 1992. The terrorists involved each time used different names to conceal their identity though they were all reportedly found to be affiliated to the same Hezbollah organization. These terrorist acts were deemed as “insurance against retaliation by the US, Syrian, and other forces.” Casualties included 230 Americans and 58 Frenchmen who they  assumed responsible for the Marine barracks and embassy bombings in Beirut.

5 Moscow Theatre Hostage Crisis

Image: Moscow Theatre Hostage Crisis
The crisis occurred on Oct. 23, 2002 when the Chechen rebels stormed the Moscow theatre during a performance demanding the withdrawal of Moscow troops from war-torn Chechnya. Chechen women sat among the hostages with explosives strapped to their bodies. After a two-and-a-half day siege, the Russian Alpha Group forces pumped an undisclosed chemical agent into the building's ventilation system and raided it.
The crisis ended on Oct. 26, 2002, after the three-day stand off which left 117 hostages and 50 Chechen militants dead.The militants and hostages reportedly died due to adverse reactions to the gas.

4 Beslan School Hostage Crisis

Image: Beslan School Hostage Crisis
Famously known as ‘the Beslan school siege’ or ‘the Beslan massacre', this attack was targeted on School Number One (SNO) a Russian town in Beslan in September, 2004. A group of armed terrorists demanding the end of the Second Chechen War took more than 1,100 people including nearly 800 children as hostages in the school.
On the third day of the stand-off, in the rescue attempt, the Russian security forces stormed the building  with tanks and incendiary rockets resulting in the deaths of over 380 people.

3 Laju Incident

Image: Laju Incident
This event, which took place in Singapore on January 31, 1974, occurred when four men armed with submachine guns and explosives assaulted the Shell oil refinery in Pulau Bukom and attempted the disruption of oil supply from Singapore to other countries. The motivation behind this act for the attackers was to avenge the oppression of the Arab masses in the Middle East. They detonated 3 of the 12 explosives they carried and hijacked a ferryboat bound for Laju in an attempt to escape and held 5 of its crew members captive. After 8 days of negotiations, they agreed to release the hostages in exchange for safe passage to the Middle East.

2 Sabena Flight 571

Image: Sabena Flight 571
It was in May,1972 when a Boeing 707 passenger plane scheduled to fly from Vienna to Tel Aviv was hijacked by a group of two men and two women from the Black September organization. The flight, captained by English pilot, Reginald Levy landed at Lod Airport where the hijackers separated the Jews from the non-Jews and sent them back to the aircraft. The hijackers demanded the release of 315 Palestinian terrorists in Israeli prisons.
A rescue operation, codenamed “Operation Isotope,” by a team of 16 commandos was carried out the next day killing the two men and capturing the two women hijackers.

1 Peshawar Army School Massacre

Image: Peshawar Army School Massacre
The massacre was executed by the Pakistani Taliban, the same group that bombed or burned over 1,000 schools and shot Malala Yousafzai, the teenage advocate for girls’ right to education in Pakistan.
On December 16, 2014, the Taliban took their war on education to a preposterous new low when they assaulted a crowded school in Peshawar that left 146 killed — 132 of them uniformed schoolchildren and 113 injured — in the deadliest single attack in the group’s history.During an eight-hour rampage at the Army Public School, a team of nine Taliban gunmen stormed through the corridors and assembly hall, firing at random and throwing grenades. Some of the 1,100 students at the school were lined up and slaughtered with shots to the head.
Eventually, all 9 insurgents were killed.