LAGOS, Nigeria (AP) — Nigerian Navy divers will help search Thursday for two people missing when a helicopter flying from an offshore oil rig crashed into a lagoon in the Nigerian commercial capital of Lagos, a rescue official said.

Rescuers recovered four bodies on Wednesday from the crash of a U.S.-made Sikorsky S-76C+ belonging to the Houston, Texas-based Bristow Group.

Six injured people from the chopper are "responding to treatment" in the hospitals, according to spokesman Ibrahim Farinloye of the National Emergency Management Agency.

"We are deploying navy divers to join us in the recovery" of two people missing in the accident, Farinloye told The Associated Press on Thursday.

Local newspapers quoted witnesses as saying that they heard an explosion before the chopper nosedived into the water and burst into flames. There were no reports of any distress call.

In a statement posted on its website, Bristow said it has set up a U.S. hotline for relatives and friends while it works to identify victims. There was no immediate news on the nationalities of those involved. Bristow charters helicopters to oil and gas companies.

The Nigerian Civil Aviation Authority said the helicopter was en route from an offshore oil rig in the south of the country when it crashed Wednesday afternoon near Third Mainland Bridge, between Victoria Island and the mainland.

The helicopter crashed on approach to Lagos' Murtala Muhammed International Airport, Bristow said.