A police officer is posted to keep the public out of the cordoned area of an explosion at The Whaler Resort. In the background near his chest appears to be the remnants of a barbecue unit. The Maui News/Gary Kubota

Authorities are investigating an explosion that happened Thursday night during a barbecue at The Whaler Resort in Kaanapali and critically injured three people.

One person was taken via helicopter to Maui Memorial Medical Center emergency room for further treatment, police said.

The explosion was strong enough to dislodge a number of items and send them flying into the air. The area of the blast was still cordoned off by authorities early Friday morning.

People in the surrounding area did not have to evacuate, the Maui Police Department said, and preliminary investigations suggested liquefied petroleum gas, which supplies barbecue grills in the resort’s common area, was involved in the explosion.

“Witness statements indicate a possible grill malfunction before the incident,” police said.

The explosion left a pile of debris at The Whaler on Kaanapali Beach, a popular tourist area where a string of hotels, timeshares and rental properties line white sands.

Small yellow flags were posted near the items in the sand. Some were more than 30 feet away from the resort property, including what appeared to be broken pieces of ceramic-looking tile.

Yellow flags mark the areas in the sand where a variety of items came to rest after an explosion at The Whaler Resort. The yellow flag marks the location of a ceramic-looking tile. In the background is a three-sided metal shield. The Maui News/Gary Kubota

Yellow flags mark the areas in the sand where a variety of items came to rest after an explosion at The Whaler Resort. The yellow flag marks the location of a ceramic-looking tile. In the background is a three-sided metal shield. The Maui News/Gary Kubota

Police said dispatch received multiple reports of an explosion at The Whaler Resort at 6:15 p.m. Thursday, and police arrived at 6:21 p.m. Authorities received assistance from bystanders with medical and first responder backgrounds providing life-saving measures and first aid until medics and firefighters arrived.

Seven individuals ranging in age from 18 to 74 were hurt in the blast with three suffering critical injuries, police said.

Authorities said the emergency response included 10 police officers, three fire companies consisting 13 firefighters, a fire investigator and a fire battalion chief, as well as a paramedic unit and Maui MedEvac.

“The official cause remains undetermined and is under active investigation,” police said Thursday night.

The Whaler said the blast happened at their Tower One barbecue area.

“Thankfully, we are actively working with the fire department to investigate the situation, and we will share updates as soon as more information becomes available,” the statement said. “Our top priority is the safety and well-being of our owners, guests, and team members.”