At least 16 people were taken to area hospitals after a footbridge collapsed late Saturday night following an Independence Day celebration at Hidden Lake Park in Merrillville. Authorities said the total number of injured was unknown.

Authorities were unable to provide further details at the scene, and said more information would be released as an investigation continues through the overnight hours.

MORE: View additional photos from the scene of a footbridge collapse in Merrillville.

The collapse took place about 10 p.m., at the end of the Fourth of July fireworks display, witnesses said.

"It happened right after the fireworks, I heard it snap," Merrillville resident Larry Hedges said.

Hedges estimated several dozen people were on the bridge, which is about 90 feet long.

Meanwhile, authorities said they were attempting to account for everyone, and a dive team continued to pull items out of the water late Saturday night.

There were estimates that thousands had attended the annual fireworks display at the park in years past.

Tom Geary, of Merrillville, said he was assisting the dive team. He said he didn't witness what he deemed serious injuries.

Ross Township firefighter Perry Herzog said the suspension bridge that stretches across the park's lake collapsed right after the grand fireworks finale, sending an unknown number of people into the water.

"They had to rescue quite a few people," said Herzog, the fire service's former chief.

Herzog said 16 people were transported to local hospitals for treatment. He said others might have been taken to hospitals by family members.

He did not know the nature of their injuries, and said there were no fatalities in the accident.

About 50 emergency vehicles responded to the scene, along with helicopter and dive teams.

The park is at the intersection of 63rd Avenue and Broadway.

Robert Walker, of Merrillville, blamed the collapse on the number of people crossing the bridge.

"It was a mass of confusion," he said. "People were walking across the bridge when it collapsed. People were grasping and hanging onto the bridge itself."