Indianapolis police believe they might know who the gunman was in the shootings at a birthday party that killed two people and injured six others.

A spokeswoman for Indianapolis Public Safety Director Frank Straub said Wednesday that investigators have identified a suspect in the shootings. The spokeswoman, Maura Leon-Barber, declined further comment.

Straub has called on the suspect to surrender.

A masked gunman armed with an AK-47 or SKS assault-style rifle opened fire early Tuesday at the birthday gathering on the city's near west side. The gunfire killed the 37-year-old woman hosting the party and a 54-year-old man who had just arrived on a bicycle.

Investigators haven't released a motive for the attack.