CAIRO (AP) — Libya’s chief prosecutor said Monday he ordered the detention of eight current and former officials pending his investigation into the collapse of two dams earlier this month, a disaster that sent a wall of water several meters high through the center of a coastal city and left thousands of people dead.

The two dams outside the city of Derna broke up on Sep. 11 after they were overwhelmed by Storm Daniel, which caused heavy rain across eastern Libya. The failure of the structures inundated as much as a quarter of the city, officials have said, destroying entire neighborhoods and sweeping people out to sea.

Government officials and aid agencies have given estimated death tolls ranging from more than 4,000 to over 11,000. The bodies of many of the people killed still are under rubble or in the Mediterranean, according to search teams.

A statement by the office of General Prosecutor al-Sidiq al-Sour said prosecutors on Sunday questioned seven former and current officials with the Water Resources Authority and the Dams Management Authority over allegations that mismanagement, negligence and mistakes contributed to the disaster.

Derna Mayor Abdel-Moneim al-Ghaithi, who was sacked after the disaster, was also questioned, the statement said.

Prosecutors ordered the eight to be jailed pending the investigation, the statement added.

The dams were built by a Yugoslav construction company in the 1970s above Wadi Derna, a river valley which divides the city. They were meant to protect the city from flash floods, which are not uncommon in the area. The dams were not maintained for decades, despite warnings by scientists that they may burst.

A report by a state-run audit agency in 2021 said the two dams hadn’t been maintained despite the allocation of more than $2 million for that purpose in 2012 and 2013.

A Turkish firm was contracted in 2007 to carry out maintenance on the two dams and to build a third one in between them. The firm, Arsel Construction Company Ltd., said on its website that it completed its work in November 2012. It didn’t respond to an email seeking further comment.

Two weeks on, local and international teams were still digging through mud and hollowed-out buildings, looking for bodies. They also combing the Mediterranean off Derna, searching for boding swept away in the floods.

The floods have left as many as a third of Derna’s housing and infrastructure damaged, according to the U.N.’s Office for Coordination of Humanitarian Affairs, or OCHA. Authorities have evacuated the most impacted part of the city, leaving only search and ambulance teams, OCHA said.

The World Health Organization says more than 4,000 deaths have been registered dead, including foreigners, but a previous death toll given by the head of Libya’s Red Crescent was at 11,300. The U.N. Office for the Coordination of Humanitarian Affairs says at least 9,000 people are still missing.

The storm hit other areas in eastern Libya, including the towns of Bayda, Susa, Marj and Shahatt. Tens of thousands of people have been displaced in the region and took shelter in schools and other government buildings.

The questioning and jailing of officials were a first crucial step by the chief prosecutor in his investigation which is likely to face daunting challenges due to the country’s yearslong division.

Since 2014, eastern Libya has been under the control of Gen. Khalifa Hifter and his self-styled Libyan National Army. A rival government, based in the capital, Tripoli, controls most national funds and oversees infrastructure projects. Neither tolerates dissent.

The Supreme Council of State, an advisory body based in Tripoli, has called for a “thorough international investigation,” echoing a call by many residents across Libya. Such call mirrors the deep mistrust in state institutions.