One shooting happened after 7:30 p.m. on Saturday at the intersection of Adeline and 16th streets near DeFremery Park.
Police found a 38-year-old man suffering from a gunshot wound.
The victim was taken to the hospital where they later died.
Oakland Mayor Sheng Thao says the shooting happened during a high school reunion.
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She issued this statement saying:
"I am deeply saddened there was a shooting at the McClymonds Alumni Action Committee reunion picnic at DeFremery Park. We will not tolerate this type of violence, especially at a peaceful annual gathering. OPD is investigating and I urge anyone who may know anything to contact the OPD Homicide section at (510) 238-3821. My heart is with the family of the victim and the entire McClymonds and West Oakland community. Ceasefire partners are actively working to prevent additional violence. Thank you to all of our first responders. #LoveLife"
Officials say the McClymonds Alumni Action picnic is an annual family friendly gathering with hundreds of people of all generations there.
The victim's name is being withheld pending notification to next of kin.
They are outraged a shooting happened during a peaceful event.
"It is unconscionable that someone would actually act in a way of violence in this way, to take someone's life during a party celebration," Thao said during a press conference.
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"We would like to extend our condolences to our fallen alumni. It is really heartbreaking to lose a member of your community, who was beloved, especially in front of the entire community," said McClymonds High School Principal Darielle Davis.
Police didn't say whether the shooting was connected to the picnic.
Investigators say there may have been more than one shooter.
McClymonds High School's principal assures parents and students that the school is safe.
Anyone with information is asked to contact the OPD Homicide Section at (510) 238-3821or the TIP LINE at 238-7950.
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Another shooting in Oakland happened earlier in the day left one person in critical condition.
It happened around 2 p.m. on Martin Luther King Jr. Way under Highway 980 near a large unhoused encampment.
Police told our media partners at the Mercury News that the victim is now recovering in the hospital from major injuries.