An explosion on a boat docked in Chesapeake City, Maryland, on Saturday afternoon left at least nine people injured, four of whom had to be airlifted by helicopter due to the severity of their injuries.

The incident occurred around 4:20 p.m. in the Chesapeake and Delaware Canal, a waterway located northeast of Baltimore, near the border with Delaware, the Maryland State Fire Marshal's Office reported.

The boat had just loaded fuel

According to authorities, the boat, a 1988 Wellcraft model with a length of 32 feet (almost 10 meters), had just refueled and was moored in front of Schaefer's Canal House seafood restaurant when the explosion occurred, the New York Times reported.

Among the injured are seven people who were on board the boat and two who were on a nearby dock. So far, authorities have not released their identities.

Maryland State Police reported that four of the injured were transported by the agency's Aviation Unit to a ChristianaCare medical center, while the others were taken by ambulance to area hospitals.

Vincent Hunter Dortenzo, spokesman for the Maryland Department of Natural Resources, said those evacuated by helicopter suffered serious burns.

So far no deaths have been reported and authorities have not updated the health status of the victims.

Wide deployment of emergency equipment

The explosion mobilized multiple response agencies, including helicopters, paramedics and more than half a dozen fire companies.

The operation included, among others, Chesapeake City Volunteer Fire Company #1, Cecil County paramedics and several specialized emergency units.

The Maryland Fire Marshal's Office confirmed that the cause of the explosion remains under investigation and said it will provide additional information as the process progresses.

Other nautical accidents marked the holiday weekend

The explosion occurred in the middle of a weekend with several boat-related incidents in different parts of the United States.

In Virginia Beach, four people were rescued Friday after their boat capsized. Authorities reported that no one suffered serious injuries.

That same day, on the Patapsco River, also in Maryland, two adults and two minors were hospitalized after their boat caught fire. One adult and one of the children suffered burns, although all were reported in stable condition.

Meanwhile, in the state of Wisconsin, three children under the age of 11 died after a boat capsized on Lake Geneva during a sudden storm. Another seven people managed to be rescued alive and the bodies of the minors were recovered after an extensive search operation.

Maryland authorities are still investigating what caused the explosion in Chesapeake City.