At least two people were killed and dozens injured in a mass shooting in Baltimore in the early hours of Sunday, officials said.

    The two people killed were adults but neither has yet been identified. Police confirmed that 28 others had been injured, three of them critically.

    "Our hearts and prayers are going out to the families, sending out to the families and friends of these victims as well as the community in our entire city," said acting Police Commissioner Richard Worley said at a news conference. 

    Police first received calls about the shooting around 12:30 a.m. Sunday.

    Nineteen people were transferred to the emergency department of MedStar Harbor Hospital, all “suffering varying degrees of injury from gunshot wounds,” said Debra Schindler, regional director of media and public relations at MedStar Health.

    “Multiple critically injured patients were evaluated and triaged simultaneously by clinical staff, while hospital security managed the throng of family members that gathered in and outside of the emergency department,” Schindler said in a statement. Nine patients were transferred on to other Baltimore trauma centers, and all but one patient has been released. 

    The University of Maryland Medical Center said in a statement that 12 patients were in their trauma center, and four more were being treated in the pediatric emergency department.

    "This was a reckless, cowardly act that happened here," Baltimore Mayor Brandon Scott told the same news conference

    "I want those who are responsible to hear me, hear me very clearly,"  Scott continued. "We will not stop until we find you, and we will find you."

    Addressing the perpetrators directly, the mayor said: "I hope, every single breath that you take that you think about the lives that you took, and you think about the lives that you impacted here tonight."

    The shooting happened at a block party in Baltimore’s Brooklyn Homes neighborhood.

    Speaking with MSNBC’s Katie Phang Sunday morning, Scott called on citizens to come forward with any information they have on the perpetrator, or perpetrators. 

    "Somebody out there knows who did this," Scott said. 

    "We need you to say something," he said. "We need you to treat this as if someone had taken the life of your son, your daughter, your father, your brother. We need you to do that and step up and do the right thing." 

    In a separate incident, seven people were shot and two more were injured after they were trampled inside the City Nightz nightclub on North Washington Street in Wichita, Kansas, just before 1 a.m. Sunday, police said. Authorities said there were no fatalities and that one person was in custody, adding that their investigation showed shots came from at least four firearms.

    The shooting victims range in age from 21 to 34, police said, adding that the two victims who sustained traumatic injuries in the trampling were a 30-year-old woman and a 31-year-old man. Emergency medical personnel brought five of the victims to local hospitals, and the others went in private vehicles, police said.

    In Chicago, in another incident, 31 people had been shot — three fatally — since 5 p.m.  Friday.