An AirAsia plane plane which went missing on Sunday with 162 people on board Sunday may be at the bottom of the sea, following presumptions that it crashed off the Indonesian coast, an official said on Monday, as countries around Asia send ships and planes to help in the search effort.

Indonesia AirAsia Flight QZ8501 went missing in Southeast Asia during a flight from the Indonesian city of Surabaya to Singapore. The craft had on board 155 passengers and seven crew on board. There were 155 Indonesians, three South Koreans, and one person each from Singapore, Malaysia and Britain. The co-pilot was French.

The Airbus A320-200 craft disappeared after its pilot failed to get permission to fly higher to avoid bad weather during a flight from the Indonesian city of Surabaya to Singapore on Sunday.

The flight did not issue a distress signal and disappeared over the Java Sea five minutes after requesting the change of course, which was refused because of heavy air traffic, officials said.

The search begun shortly after the disappearance was confirmed, with Singapore and Malaysia offering to help in the process.

There were reports of a crash east of Belitung Island, Indonesia, but it was not confirmed to be the missing #QZ8501, according to local media.

“Based on our coordinates, we expect it is in the sea, so for now (we think) it is on the sea floor,” Soelistyo, head of Indonesia’s search and rescue agency, told reporters when asked about the missing plane’s likely location.

A senior Indonesian civil aviation source told Reuters that authorities had the flight’s radar data and were waiting for search and rescue teams to find debris before they started their investigation into the cause.

Air force spokesman, Hadi Tjahjanto, said searchers were checking a report of an oil slick off the east coast of Belitung island, near where the plane lost contact. He also said searchers had picked up an emergency locator signal off the south of Borneo island but had been unable to pinpoint it.