An explosion was spotted in waters off Sand Island Tuesday afternoon.
Smoke could be seen from miles away.
Officials said the explosion was triggered by the disposal of old fireworks.
According to the state Department of Land and Natural Resources, a federal agency hired Fireworks by Grucci Hawaii to dispose of surplus fireworks from a deadly Waikele bunker explosion that killed five men in 2011.
The Division of Boating and Ocean Recreation issued a marine event permit for Tuesday, between 11:15 a.m. and 4:30 p.m. for the fireworks to be shot off a barge approximately 1,500-2,000 feet offshore.
DOCARE had a crew in the water to keep boaters a safe distance away.
The Honolulu Fire Department and U.S. Coast Guard were notified, but as far as we know, there was no advance warning to the public.
The state says another permit was issued for next month.
The company that destroyed the fireworks says it will happen again on July 14 off the Reef Runway.