The International Organisation for Migration (IOM) said Friday that guards at a detention center in the Libyan capital Tripoli had shot dead at least six migrants, reports DW.

Federico Soda, head of the Libyan mission of the IOM, said he couldn’t exactly say what led to the shooting, but it was “related to overcrowding and the terrible, very tense situation” at the detention facility.

Several other migrants were wounded and lots more escaped the facility.

Soda told the AFP news agency that guards had fired into the air to control previous incidents of chaos at a detention facility during the week.

Tense build-up at detention centers over the week

The shooting came a week after Libyan security forces carried out raids on houses and temporary shelters in Gargaresh, a poor suburb of Tripoli. The area is heavily populated by migrants and asylum-seekers.

Doctors Without Border (MSF) said that at least 5,000 migrants had been “detained during violent mass arrests across the city since October 1.”

There are hundreds of thousands of migrants in Libya, some seeking to travel onwards to Europe and others looking for work in the major oil-producing country.