Yemenis inspect the site of a suicide bombing targeting a recruitment center in the southern port city of Aden on Aug. 29. (European Pressphoto Agency)

A suicide bomber detonated a vehicle packed with explosives Monday in a mustering area for army recruits in the port city of Aden in southern Yemen, killing at least 54 people, according to the Health Ministry.

The attack, one of the worst suicide bombings to hit this country, took place in the al-Sanafer neighborhood and was claimed by the Islamic State extremist group through its Amaq news agency.

The Health Ministry in Aden told the Reuters news agency that in addition to the dead, 67 people were wounded.

Many of the wounded were treated at a hospital run by Doctors Without Borders just a mile from the blast site. The humanitarian group said it had received 45 bodies.

“Around 8:15 [a.m.], we heard a great explosion that shook the building of our hospital, and we came to know that it occurred at a military camp,” said the group’s communication officer in Aden, Malak Shaher, adding that the injuries ranged from critical to minor.

People gather at the site of a suicide car bombing in Yemen’s southern city of Aden on Aug. 29. (Wael Qubady/AP)

The chairman of Yemen’s Center for Human Rights Studies, Mohammed Qasem Noman, said it was difficult to pin down the toll because the wounded were going to different hospitals around the city.

“The explosion took place at a local government school where new recruits were signing up to join the military,” he said.

Yemen, the poorest country in the Arab world, has been wracked by a multi-sided battle pitting government forces against Shiite Houthi rebels in the north.

Extremist Islamist groups, including al-Qaeda and the Islamic State, have taken advantage of the fighting to gain territory and launch attacks on both sides.

Marwan Abu Murad, 38, a Customs Authority employee in Aden who lives about half a mile from the scene of the bombing, said area residents told him the attack occurred when a military food truck entered the compound of a government school that had been turned into a recruitment base.

“Immediately after the food truck entered, a Toyota Hilux pickup truck stormed in and exploded,” Abu Murad said.

Another local resident, Faisal Abdul Hafeth al-Doqm, a 30-year-old lawyer, said the Islamic State released a statement on local news websites saying it was behind the attack and identifying the suicide bomber as Ahmed Saif, a man of Somali descent who was born and raised in Aden.

Yemeni security officials confirmed the identity of the attacker and distributed a photo of him smiling and holding an assault rifle next to a flag used by Islamist extremists, the Associated Press reported.

In May, suicide bombers in Aden killed at least 45 army recruits lined up to enlist.

Saudi Arabia is leading an Arab coalition that is backing the internationally recognized government of President Abed Rabbo Mansour Hadi and carrying out airstrikes against the Shiite rebels, whom it says are backed by Iran.

An estimated 3,500 civilians have been killed in the fighting during the past 18 months and about 3 million people have been displaced, according to the United Nations and aid groups.

Peace talks mediated by the United Nations in Kuwait were suspended in early August, and the fighting has continued unabated.

On Thursday, U.N. High Commissioner for Human Rights Zeid Ra’ad al-Hussein called for an international investigation into the serious allegations of abuses committed by “all sides” in the conflict.

On Aug. 18, after the aerial bombing of one of its hospitals in the north of the country, Doctors Without Borders announced that it was evacuating its staff from hospitals in two northern provinces.

Before the announcement, the group was active in 11 hospitals and provided support to 18 others across the country. Yemen represents one of the charity’s largest missions in the world.

Schemm reported from Addis Ababa, Ethiopia. William Branigin in Washington contributed to this report.