CHARLOTTE, N.C., JUNE 7 -- Gunshots of unknown origin struck two girls in a pool at a theme park jammed with thousands of visitors, killing one girl and leaving the other, a 6-year-old, critically injured, officials said.

"At this point, we have no witnesses who can identify where the gunfire came from," Mecklenburg County Assistant Police Chief R.D. Ferrell said.

Police used a helicopter and dogs to search the Carowinds theme park after the shootings, and investigators believe the gunfire may have come from outside the park, about 10 miles south of Charlotte, Ferrell said.

About 2,000 people were at the Ocean Island section, a simulated beach, when the shooting occurred, said Carowinds spokeswoman Claire Lang.

The dead girl was identified as Michelle Ann Sexton, 16, of Rock Hill, Charlotte Memorial Hospital authorities said. The second victim, identified as Alesha Rollins of Charlotte, underwent surgery this afternoon for a gunshot wound to the abdomen and was listed in critical but stable condition this evening, they said.

Ferrell said at a news conference tonight that police had no suspects or motives in the shooting.

Police are theorizing that the two may have been shot by someone who was target shooting outside the amusement park, he said.