Secretary of State Marco Rubio said the U.S. would conduct an independent investigation before responding. Four people on the boat were killed, the Cuban Interior Ministry said.

Cuba said its military killed four Cubans from the United States who were on a boat that entered its territorial waters Wednesday, which the Interior Ministry called a "foiled armed infiltration."

The boat, which was registered in Florida, “was carrying 10 armed individuals who, according to preliminary statements from those detained, intended to carry out an infiltration for terrorist purposes,” the Cuban Interior Ministry said in a statement.

“Assault rifles, handguns, improvised explosive devices (Molotov cocktails), bulletproof vests, telescopic sights, and camouflage uniforms were seized,” it said.

The ministry said that the incursion happened Wednesday morning and that a commander of the Cuban border guard was injured, in addition to six people on the U.S. boat.

All members of the group were “Cuban residents of the United States,” according to the ministry.

On Thursday, Cuban president Miguel Díaz-Canel said in a statement posted on X that it will defend itself against any “terrorist and mercenary aggression that seeks to undermine its sovereignty and national stability.”

Secretary of State Marco Rubio said earlier Wednesday the U.S. would carry out an independent investigation before it responded.

“We’re going to find out exactly what happened here, and then we’ll respond accordingly,” Rubio said from St. Kitts and Nevis, where he was attending a conference with Caribbean leaders.

Rubio added that a shootout in the open sea was "highly unusual" and that the Department of Homeland Security and the U.S. Coast Guard were both investigating.

“It’s not something that happens every day. It’s something, frankly, that hasn’t happened with Cuba in a very long time,” Rubio said.

The Cuban ministry said the people on the U.S.-registered vessel initiated the firefight, which took place 1 nautical mile northeast of El Pino channel off Cuba’s north coast.

“When a surface unit of the Border Guard Troops of the Ministry of the Interior, carrying five service members, approached the vessel for identification, the crew of the violating speedboat opened fire on the Cuban personnel, resulting in the injury of the commander of the Cuban vessel,” the ministry said.

The government department named one of the people killed as Michel Ortega Casanova. He fell into an "obsessive and diabolical" quest for Cuba’s freedom, his brother, Misael Ortega Casanova, told The Associated Press.

He said his brother was a truck driver and an American citizen who had lived in the U.S. for 20 years and was married. "Only us Cubans who have lived over there understand," he said.

The ministry also listed the names of the six people who it said had been detained. It said most have criminal histories.

The injured people were evacuated and received medical assistance, according to the statement.

Rubio said most of the information the U.S. has about what happened "is what Cuban authorities are providing both the public and the U.S. government."

The Cuban border guard alerted the U.S. to the incident Wednesday morning, and Rubio was notified at that time, he said.

Asked whether any U.S. personnel were involved in the incident, Rubio replied, “No.”

Tensions between the U.S. and Cuba have heightened over the Trump administration’s restriction of oil shipments to Cuba, especially from Venezuela, though the U.S. announced Wednesday it would allow some sales to Cuba’s private sector.

Several Florida officials have called for an investigation into the incident.

State Attorney General James Uthmeier said on X that he has "directed the Office of Statewide Prosecution to work with our federal, state, and law enforcement partners to begin an investigation." He added that the "Cuban government cannot be trusted."

Rep. Carlos Gimenez, R-Fla., called the confrontation a "massacre" and said the U.S. must determine what happened and whether any citizens or U.S. residents were victims.

Similarly, Rep. Debbie Wasserman Schultz, D-Fla., called for an investigation and said the Cuban government's version of events could not be trusted "without scrutiny."

"My office has contacted the State Department for more information, but it’s notable that this occurred in spite of ongoing Trump Administration negotiations with the Cuban regime," she said on X.