OAKLAND -- Five men who were shot in the legs at a birthday party East Oakland on Sunday night are expected to recover, police said Monday.

The shooting followed four homicides in less than six hours on Friday and was part of a string of 11 nonfatal shootings reported throughout the weekend.

Police said the killings and possibly some of the weekend shootings are linked to ongoing battles between "several identified groups" that are responsible for at least 90 percent of the shootings and deaths over the last six months.

In Sunday's incident, police said more than a dozen people were in a front yard and others were inside a home in the 2600 block of Seminary Avenue celebrating a woman's 25th birthday when a someone shot at the crowd from across the street just before 8 p.m.

The gunman was seen running away from the area, police said.

Four of the victims, ages 19, 20, 21 and 27, are Oakland residents. The fifth, a 20-year-old man, is from Richmond. They were taken to area hospitals and are expected to recover, police said.

In addition to the home, some parked cars were also hit by gunfire, as well as the nearby East Oakland Leadership Academy school, which was closed at the time.

No arrests have been made in the shooting.

Staff writers Katie Nelson and Erin Ivie contributed to this report.