At least 30 people were shot overnight in a mass shooting in Baltimore, leaving two dead and three others in critical condition, WBAL-TV reports.

Authorities started receiving calls shortly after 12:30 a.m. about the shooting at a block party in Brooklyn, Baltimore, near the 800 block of Gretna Court.

An 18-year-old woman died at the scene and a 20-year-old man died at a hospital, according to Reuters. Medics rushed nine others to area hospitals, while as many as 20 other people sought medical attention on their own.

No arrests have been made, but police are interviewing witnesses and reviewing video footage in an effort to identify those responsible.

Acting Baltimore Police Commissioner Rich Worley described the crime scene as “extensive,” according to Fox 5, which reported that the scene spans multiple city blocks. Debris was scattered throughout as people ran for safety.

Large crowds were reportedly in the area for a local event called “Brooklyn Day.” People in the area initially thought they were hearing fireworks given the Fourth of July holiday, but later realized they were hearing gunfire.

“They just kept going off,” one witness told Fox 5 of the gunfire.

Baltimore Mayor Brandon Scott is urging anyone with information to come forward.

“This is an absolute tragedy that did not have to happen,” Scott said, according to WBAL-TV. “Anyone that knows anything about what happened here, anything about this mass shooting, to come forward with any piece of information. Treat this as if it was your family and how you would want people to treat it as as if you were mourning, as if this were an event happening in your community.”

He added: “We will not stop until we find those cowards who decided to just shoot dozens of people, causing two people to lose their lives, and we’re going to be here until we find them.”

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[Feature Photo: Baltimore Police Department via AP]