CHICAGO (AP) — An off-duty Illinois State Police trooper and a woman were shot dead in a car on Chicago’s South Side on Monday, the agency said.

Trooper Antonio Alvarez, 30, and Amanda Alvarez, 31, of Chicago were found inside a non-department issued vehicle and were both pronounced dead at the scene, state police said.

The relationship between the two wasn’t clear.

Both had been shot in the head, police said. They were discovered around 1:40 p.m.

A gun was found at the scene, Chicago police said.

Antonio Alvarez was a three-year veteran of the Illinois State Police, the agency said.

The Chicago Police Department is handling the investigation.