OAKLAND -- Three men fatally shot between Wednesday night and Saturday morning in different parts of Oakland have been identified by police.

An 18-year-old man killed Saturday morning in the 8000 block of Ney Avenue in East Oakland was identified Monday as Alquino Rivera, who lived in the area. Rivera was in a car when he was shot about 11:09 a.m. Saturday by someone in a passing car, Sgt. Randy Brandwood said.

The shooter fled in the vehicle. Police later detained a possible suspect but have not charged anyone yet. A motive has not been determined.

A 22-year-old man slain Friday in the 1000 block of Mandela Parkway in West Oakland was identified as Roger Warrick, who lived nearby. Warrick was killed just after 6 p.m. by someone who approached him on foot and fled before police arrived.

A man shot late Wednesday night near his home in the 1500 block of 80th Avenue in East Oakland was identified as Ahmad Belton, 43. Belton was shot about 11:57 p.m. Wednesday and died early Thursday at a hospital.

Police have not made any arrests and motive has not been determined in the Wednesday and Friday slayings.

Oakland now has 59 homicides in 2013, compared to 68 at this time last year.

Police and Crime Stoppers of Oakland are offering up to $10,000 in reward money in each case. Anyone with information may call police at 510-238-3821 or a tip line at 510-773-2805.