More than 40 Kenyan police officers were killed in an ambush over the weekend by a group of cattle thieves in Kenya’s northern town of Baragoi.

The officers were attacked last Saturday as they pursued the thieves. As of Monday, the number of dead had risen to 42 as more bodies were found. The death toll is expected to increase since only 50 of some 100 officers mobilized to catch the thieves have returned from the mission.

Kenya’s Ministry of State for Provincial Administration and Internal Security described the recent incident as the worst single attack on police in Kenya’s history. The ministry added that it will track down those responsible and bring them to justice.