BATON ROUGE, La. (BRPROUD) — The Baton Rouge Police Department is putting a moratorium on late-night helicopter flights in the wake of a deadly crash killing two officers.

A BRPD spokesperson said the reasoning for the temporary stop is to allow the department to review its policy and practices on helicopter use.

Sgt. David Poirrier, 47, and Cpl. Scotty Canezaro, 38, died in a helicopter crash on Sunday while assisting officers in a police chase after a suspect in West Baton Rouge Parish. A preliminary report from the FAA said the Robinson R44 helicopter’s tail rotor hit a tree before crashing into a field.

The National Transportation Safety Board said the crash happened at 2:39 a.m. 10 miles away from Baton Rouge. Investigators have flight track data and are looking into communications between dispatch and air traffic control. The investigation could take 12 to 24 months.

Investigators are looking into three broad areas — the pilot, the operating environment and the aircraft itself.

A preliminary report is expected to be released in two to three weeks.