Three Maine residents were killed in a boating incident over the weekend in Cape Coral, Florida, according to News Center Maine.

Craig Millett, 56, and his wife, Brenna Millett, 49, along with Rebecca Knight, 48, all died after the 39-foot speedboat they were on flipped over on the Caloosahatchee River at 5 p.m. Saturday, the Florida Fish and Wildlife Conservation Commission confirmed.

News Center Maine said all three of the people who died were Cape Coral residents who also lived in Maine. A fourth person who was on the boat, remained hospitalized in critical but stable condition on Monday.

The cause of the crash remains under investigation.

Witnesses said they saw the boat flip over, possibly due to the wind, Bradley Johnson of the Florida Fish and Wildlife Commission said. He said it appears the outboard motors came off the boat during the crash, but he is not yet sure how fast the boat was going.

The U.S. Coast Guard, Cape Coral police and fire and Lee County emergency services all reported to the scene of the incident on Saturday night. The investigation is being led by the Florida Fish and Wildlife Conservation Commission.