OAKLAND — A shooting erupted at an all-ages birthday party at an Oakland art gallery early Sunday morning, leaving two dead and another wounded, homicide detectives said.

The names of the dead men, both believed to be from Berkeley, were not released. One of the victims was 20 years old and the other was 22. A 24-year-old man was wounded. The youngest victim was found shot inside the gallery, and the other two were found outside, police said.

Officers responded at 12:53 a.m. to reports of gunfire in the 300 block of 15th Street between Harrison and Webster streets, Oakland police Officer John O’Reilly said. Police said it appears a dispute started with at least two gunmen firing inside the gallery.

The two men killed were pronounced dead at the scene. The wounded man was able to run a few blocks away to the 1700 block of Webster, where police found him. Another man suffered cuts when he ran into a plate-glass window, apparently trying to avoid the gunfire.

According to police, officers who were already nearby in the 1400 block of Webster Street heard the gunshots and responded, but the suspects had already fled by the time they arrived. Police still don’t have a motive for the shooting and have not made any arrests. Other businesses on the block were hit by gunfire, but no other injuries were reported.

The party for a man’s 20th birthday, promoted on social media as part of a series of neighborhood parties and believed to have been attended by up to 100 people, was at Prime Development, an art gallery and vintage clothing store that occasionally hosts underground concerts.

A group of young people who attended said they began running away as soon as they noticed a group of people arguing outside the party in the street.

The homicides are the 44th and 45th homicides of the year that the Oakland Police Department is investigating. Last year at this time there were 53 homicides. Oakland police and CrimeStoppers of Oakland are offering up to $25,000 in reward money for information leading to the arrests of suspects involved. Anyone with information can call police at 510-238-3821 or CrimeStoppers at 510-777-8572. Check back for updates.

Staff writer Harry Harris contributed to this report. Contact George Kelly at 408-859-5180 or follow him at Twitter.com/allaboutgeorge.