An official said: 'Something did happen but we are not sure exactly what'

Investigators have admitted they have no idea what happened

Police, firefighters and bomb squad are investigating at the scene

Officials have admitted they have no idea what happened when a 50-year-old woman was catapulted into the air after an 'explosion' on a Rhode Island beach.

The blast - which occurred at Salty Brine Beach at around 11.15am on Saturday - threw the victim several feet off the sand and on to rocks forming the beach's jetty, authorities said.

It prompted law enforcement to evacuate the beach, with witnesses suggesting a bomb might have gone off.

But after an on-site investigation, police have been left baffled by the bizarre incident after finding no devices that could have been set off.

The woman, who has not yet been named, was taken to South County Hospital in an 'alert and conscious' state. Her current condition remains unknown.

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Baffled: Officials have admitted they have no idea what happened when a woman was catapulted into the air after an 'explosion' on a Rhode Island beach. She is pictured on a stretcher being taken to hospital

Cordoned off: Families at Salty Brine Beach watch as officials investigate the cause of the blast, which happened at around 11.15am on Saturday

The explosion threw a 50-year-old woman several feet into the air and on to the rocks of the jetty, officials said. She is being treated at South County Hospital but her condition remains unknown

Police revealed they were not looking for a suspect on Saturday night, insisting there was no danger to the public.

Investigators initially thought a culprit who was seen carrying two bags towards the scene may hidden the device in the sand then fled toward Rogers Williams beach, Sgt Thomas Silvia, of the Department of Environmental Management (DEM), said.

But later, police dispelled any suggestion they were looking for a person of interest after they discovered the bags' contents - sea shells.

Larry Mouradjian, DEM's associate director for natural resources, said: 'Something did happen but we are not sure exactly what.

'I can tell you there was definitely a ground disturbance there,' he added, 'some ground force.'

Investigators added that explosion patterns in the sand were like 'fractures'. They also said it was not connected to a series of recent boat fires in the area.

There are suggestions it could have been a gas explosion, with beach-goers saying they could smell chemicals such as sulphur and butane in the aftermath.

Others have however claimed it could have been a natural occurrence.

The DEM released a statement on Twitter late Saturday saying: 'On-site investigation compete [sic] & no reason to believe there are an [sic] public safety concerns related to incident.

Police and firefighters were alerted to the explosion in Narragansett this morning after several beachgoers dialed 911, it is reported.

The bomb squad were then called to the popular beach.

Mario Lewis, from West Greenwich, told the Providence Journal he was catching crabs on the beach when he heard a 'boom' in the sand next to the rock wall.

'It was like an M-80 boom, like a grenade,' he added.

He added that there was no debris or black smoke in the aftermath.

Search: Police are hunting for a possible suspect they believe may have planted an explosive device in the sand. Above, officials walk along a populated part of the beach, further down from where the blast occurred

Popular: Salty Brine Beach, seen in an aerial shot, is being pored over by bomb experts

Dave Dean, a local radio host who was on the beach when the explosion occurred, said he initially thought the noise was a 'small tremor or something' - but then he heard shouts of 'call 911!'.

'I started hearing people start yelling 'Call 911' because a lady got hurt in the incident. I saw a lady on the ground, and after about 20 minutes they asked us to get off the beach,' he told ABC.

It was like an M-80 boom, like a grenade' Beachgoer Mario Lewis

'I walked over to try and take a look at what happened. There was what looked like a sink hole. ... If you had dug a hole and put some sand over it that's what it looked like.'

Another person on the beach at the time, Stacey Beal, told reporters she could smell a gas odor.

She said the injured woman was thrown into the air by the explosion, which caused sand to 'blow up out of the ground'. However, the victim was alert when she was taken to hospital, she said.

Rayna Maguire, of the DEM, confirmed the blast 'blew a 50-year-old woman on to the rocks'.

The beach was immediately closed to visitors. Police cordons remain in place.

The investigation is ongoing.