Image copyright US Navy via Reuters Image caption None of the 21 people who were injured sustained serious injuries

A passenger plane slid off a runway in the US state of Florida on Friday night, ending up in a river after landing during a thunderstorm.

Twenty-one people were taken to hospital with minor injuries, officials said.

The chartered Boeing 737, operated by Miami Air International, had flown from Guantanamo Bay in Cuba to a military base in the city of Jacksonville.

Passengers say it landed heavily in the storm, skidding into St John's River.

The 136 passengers and seven crew members on board evacuated the Boeing 737-800 via its wings.

"No fatalities reported. We are all in this together," Jacksonville Mayor Lenny Curry wrote on Twitter after the incident.

He also said President Donald Trump had offered assistance as the situation was developing.

On Saturday a spokeswoman for the US Navy in Jacksonville said that at least four pets checked into the luggage area were presumed to have died due to flooding.

"There's water in the cargo hold," Kaylee LaRocque told USA Today.

"We are so sad about this situation, that there are animals that unfortunately passed away."

'Terrifying' moment

One passenger on the plane, Cheryl Bormann, described the "terrifying" moment it slid off the runway.

"The plane literally hit the ground and bounced - it was clear the pilot did not have total control of the plane, it bounced again," she told CNN.

Image copyright US Navy via Getty Image caption The airliner is contracted by the US military to travel to Guantanamo Bay

Image copyright Handout via Reuters Image caption The passengers and crew were evaluated in a nearby aircraft hangar

"We were in the water. We couldn't tell where we were, whether it was a river or an ocean," she said, adding that she could smell jet fuel leaking into the river.

In a news conference, Captain Michael Connor, commanding officer at Naval Air Station Jacksonville, said it was a "miracle" that there had been no serious injuries or fatalities.

Miami Air International is contracted by the US military for its twice-weekly "rotator" service between the US mainland and Guantanamo Bay, Bill Dougherty, a base spokesman said.

Image copyright Handout via Reuters Image caption A National Transportation Safety Board (NTSB) investigator is seen with flight data recorder

Officials say the people on Friday's flight included civilian and military personnel.

Boeing released a statement sharing its "well wishes" with those on board.

It said it was providing technical assistance to the US National Transportation Safety Board, which is investigating the incident.

The aerospace giant has been under increased scrutiny following two fatal crashes involving its 737 Max 8 planes - a different model to the one involved in the incident on Friday.