A married couple and their friend tragically died after their boat flipped and capsized in a Florida river, according to police. 

Craig and Brenna Millett, of Biddeford, Maine, were enjoying fun in the water on November 29 in the Caloosahatchee River in Fort Myers with two of their friends, Rebecca Knight and Neal Kirby, when their 39ft vessel suddenly overturned. 

The four of them were inside the speed boat when the tragedy struck around 4pm near the Cape Coral Yacht Club, officials with the Florida Fish and Wildlife Conservation Commission said. 

According to witnesses, just before the boat flipped, it appeared it had been racing another vessel at high speed in the water, WGME reported. 

Both Brenna, 49, and Rebecca, 48, were found near the boat after it capsized. The friends later died at the hospital. 

Craig, 56, was found dead the following day during an underwater search. He and his wife leave behind two adult children who live in Maine. 

Kirby, who miraculously survived the horror incident, remains in critical condition. As of Monday he underwent surgery, was taken off of life support and is improving, his father told the outlet.

Officials said video footage showed the bottom of the boat visible above the water, supporting several reports that the vessel flipped, 11Alive reported. 

The cause of the accident has not yet been determined and it is unclear if drugs or alcohol were involved. The boat has been recovered and taken in for inspection as part of the ongoing investigation. 

The Daily Mail contacted the Florida Fish and Wildlife Conservation Commission for comment. 

The couple, who lived part time in Cape Coral where they were renovating a home, were experienced boaters known for spending a lot of time in the water, their friends said. 

They had built a great life there and made a lot of friends, Owen Williams, a childhood friend of Craig's, told the outlet. 

Rebecca was one of those friends the couple met in the Sunshine State. The three of them grew close after learning they were all from Maine, Williams said. 

The trio have been remembered as 'extraordinary' community members who volunteered for 'Family Initiative,' an organization that supports autistic children. 

The group made a heartbreaking post about their deaths, calling them 'fierce advocates and deeply passionate champions of Family Initiative and the autism community.' 

'Their service, generosity, and unwavering belief in our mission inspired us every single day. Rebecca’s infectious laugh and steadfast determination, Brenna’s warm smile and kind, encouraging words that lifted us through every event meeting, and Craig’s boundless generosity and immense heart, especially for our guy Kolby, touched us in ways words can barely capture,' the organization added. 

Kirby also volunteered for the group alongside his friends. 

The late husband and wife worked in the real estate industry. Brenna has been described as a 'talented and dedicated agent,' according to their obituary. 

'Her professionalism was matched only by her kindness, generosity, and the genuine care she showed for those around her,' it read. 

'Craig, her devoted partner, shared her passion for life, his strength, and his love leaving an indelible mark on all who had the privilege of knowing him. 

'Together, they were a beacon of love, support, and joy, touching countless lives with their energy, compassion, and unwavering devotion to each other and their community.' 

It is unclear when the couple is set to be laid to rest. 

Rebecca has been remembered as 'friendly, loving, and giving,' a friend said of her in an emotional Facebook post. 

Another shared: 'Beak…we love you and will miss you the rest of our lives!' 

Her funeral is scheduled for December 12.