Eight people were taken to the Martha’s Vineyard Hospital with injuries after a second-story deck collapsed at a private home in Edgartown during a Fourth of July party Monday night.

The incident triggered an Islandwide EMS response due to the number of people involved, Edgartown police Sgt. Joel DeRoche said on Tuesday.

Sergeant DeRoche said police were called to 37 Mill Hill Road at 9:10 p.m. Thursday, where the deck with about 20 people on it had collapsed. He said a Fourth of July party was in progress, and fireworks had just begun over the Edgartown harbor.

Eight people were transported to the hospital with injuries, some with serious injuries, Sergeant DeRoche said. The initial response was from Edgartown police, fire and EMS. Due to the number of people involved, a mass casualty incident was declared and ambulances responded from various Island towns.

Ambulances from Edgartown, Oak Bluffs and Tisbury made the hospital transports while West Tisbury stood by at the Martha’s Vineyard Airport, Sergeant DeRoche said. Clevelandtown Road was closed for a time during the response due to the limited access to Mill Hill. “It’s tight quarters on that road,” Sergeant DeRoche said.

The sergeant said he had spoken with the Edgartown fire chief and left a message for the town building inspector, who will conduct a followup inspection on the property.

Edgartown assessor records show that the home is owned by Karen E. Zingg. The house was built in 1998.

Sergeant DeRoche said he believed most of the people injured were treated and released from the hospital, and that one injured person may have been flown to Boston for treatment. All the people injured were adults.

He also said he believed the party was hosted by the homeowner.