(CNN)-- A July Fourth outing to watch fireworks from the water turned into a disaster Wednesday night when a boat capsized off Long Island, leaving three children dead.
The three, who were found inside the cabin, include a 12-year-old boy and two girls ages 8 and 11, said Det. Lt. John Azzata of Nassau County police.
The 34-foot-long vessel had 27 people on board, Azzata said.
Officials are looking into whether the boat was overcrowded, he said.
People in nearby boats jumped into the water to try to save as many people as possible, and authorities quickly dispatched divers after receiving a 911 call shortly after 10 p.m. ET, Azzata said.
The cause was not immediately known.
The boat began sinking in 21 feet of water, then drifted about seven-tenths of a mile. It ultimately sank in 60 to 70 feet of water, he said.
The incident took place just inside Cold Spring Harbor in Oyster Bay.
The nearby Atlantic Steamer Fire Co., an all volunteer force, recovered the body of one victim; the other two were recovered by Nassau County police scuba divers.
The boat was being operated by two people -- the owner and a relative -- and there is "no evidence or suspicion of any intoxicants being utilized," Azzata said.
Authorities are investigating whether there was a life jacket or life preserver for each person as required by law, he said. While children under age 12 are required to have life jackets on, that requirement does not apply when they are inside a cabin, he said.
All three victims have different last names. It was not immediately known if they are related, Azzata said.
Other survivors were transported to a nearby hospital.
Investigators are working to recover the boat, which was "a very recent purchase," Azzata said.
The fireworks show that the boat was returning from had received a permit, he said.