The police have said the collapse of the Baltimore bridge in the United States on early Tuesday morning after a collision with a cargo ship could not be linked to terrorism.

“There is absolutely no indication that there’s any terrorism, that this was done on purpose,” said Baltimore Police Commissioner Richard Worley.

Footage showed a 300-meter vessel hitting the Francis Scott Key Bridge, bringing the steel-built structure crashing into the Patapsco River.

The footage also appeared to disclose that the ship went dark twice in the moments before the collision, possibly indicating some kind of power failure on board.

Meanwhile, authorities said the emergency response had been swung into action after the collision, which happened around 1:30 am (0530 GMT), with first response vehicles crowding the shoreline.

Water temperatures were around 48 Fahrenheit (9 Celsius), narrowing the window of survivability.

Baltimore’s fire chief James Wallace said sonar had “detected the presence of vehicles” in the harbour, but declined to estimate how many.

One person was taken to hospital in “a very serious condition,” he said, adding a second person recovered from the water was uninjured.

“We may be looking for upwards of seven individuals,” he added.

Reports said a search and rescue operation involving divers, boats, aircraft and sophisticated sonar and infrared equipment has been deployed.

The lights from multiple vehicles can be seen on the bridge in the CCTV footage seconds before the collapse. Some contractors were working on the bridge at the time, Maryland officials said.

The managers of the Dali, Synergy Marine Group, said that none of the crew were injured.

Some experts suggested the bridge’s main support structures may not have been properly protected to withstand a collision by such a large vessel.

“The significant momentum of this massive cargo vessel, especially when laden with cargo, would have been considerable upon impact,” said Professor Toby Mottram, a structural engineer at the University of Warwick.

“It’s evident that the pier couldn’t withstand the impact energy… The extent of the damage to the bridge superstructure appears disproportionate to the cause, a matter for future investigation,” Mottram said.