A town in Florida’s western panhandle is coming to terms with a murder in which a team of up to eight men broke into the home of a couple known locally for caring for disabled children and shot them in front of their family.

Police investigating the double murder in Pensacola, near the border with Alabama, said the break-in and killing was organised with military precision. Melanie and Byrd Billings were shot a number of times last Thursday, when nine of their children were in the house.

The Billings were well-known locally because in addition to four biological children they had adopted 12 children with conditions ranging from autism to Down’s syndrome. Some in the town referred to the parents as “angels”.

Three men were in custody last night over the murders: Wayne Coldiron, a labourer, 41; Leonard Gonzalez Jr, 35, who was arrested in Florida, and his father, 56, also called Leonard.

Two other men were being questioned yesterday, and police said they were searching for a further three.

Coldiron and the younger Gonzalez have been charged with murder.

The investigation has been aided by the fact that the couple had installed CCTV cameras in every room and around the house as a security measure for their children.

Footage recorded by one outside camera showed a large red van pulling up to the front door of the house. The van deposited three men dressed in black clothes and masks who entered the house, while two others, also dressed in black, came out of hiding in nearby woods and entered via an unlocked door at the back.

Sheriff David Morgan, leading the investigation, told reporters the break-in and shootings took barely 10 minutes. “I think you’ll find this particularly chilling, and here’s why: we have a team that enters at the rear of the home and another that enters at the front of the home,” he said.

Three of the nine children at home at the time witnessed the intruders and one ran out of the house and alerted a neighbour who called the police. None of the children, all aged between eight and 14, were hurt.

Morgan said the mastermind of the killings was among the three men in custody, though he would not identify him. He added there were many possible motives for the attack, one of which was robbery.

A clue to the possible motive was found by the local paper, the Pensacola News Journal, on the MySpace page of Leonard Gonzalez Jr. It was last updated on Wednesday, a day before the murders.

His last profile status reads: “Making a move for humanity.” On his page he wrote about his eight-year-old daughter Mary Gonzalez whom he refers to as Bella. “She was taken from me, against my will, several years ago and I miss her very much.”

In a post on 6 July titled “We are getting closer” he tells his daughter she will be returned soon to her “true loving family”.

He went on: “Not only are you descended from aristocracy … you have the DNA and family lineage to back up whatever dreams you may have.”

According to police, the elder Gonzalez has admitted acting as the getaway driver, remaining in the van while others entered the house. Warrants suggest that he has also alerted police to the involvement of several other men.

Gonzalez Sr has been charged with tampering with evidence after he allegedly tried to paint over the van to disguise it. His bail has been set at $500,000 (£300,000).

An adult daughter of the Billingses, Ashley Markham, said the younger children were now being cared for together with family and friends at an undisclosed location.

She said there was no known connection between anyone in their family and the three men being held in custody.