The victim count in Sunday’s shooting at an after-prom party in Texas has risen to 11, and four “people of interest” have been identified, officials said Tuesday.

The number of victims in Jasper County was initially believed to be nine. Authorities discovered the additional victims after they sought treatment the next day, Jasper County Sheriff Mitchel Newman said at a news conference.

Eight of those struck by gunfire have been released from hospital care, Laronnia Gray, Jasper County’s victim assistance coordinator, said at the news conference.

It wasn’t clear whether the additional victims were also struck by gunfire. Gray said all the victims were “physically injured.”

The 11 victims were ages 15 to 19, officials said.

The so-called people of interest have not been arrested, officials indicated. Investigators were still interviewing witnesses and trying to pinpoint a motive, Newman said.

“We expect to be seeing an arrest warrant and warrants soon,” Jasper County District Attorney Anne Pickle said at the news conference.

Newman, the sheriff, said a statement with updates on the case was expected to be released Wednesday.

Authorities found at least one vehicle believed to be connected to the case and seized it for processing as possible evidence, Newman said.

The attack unfolded shortly after midnight, authorities said. Whoever opened fire was gone when deputies arrived, he said.

A second shooting in which no one was struck was reported at about 12:45 a.m. in the city of Jasper, Newman said. A vehicle seen at the after-prom party attack was also seen at the second shooting, he said.

It wasn’t clear whether authorities were processing that vehicle. Sheriff’s spokesperson Karli Cherry indicated more than one vehicle may have been seen at both locations.

“The vehicles that were involved in the secondary shooting were present at the party, as well,” she said, “and we’re investigating that possible connection.”