A Qantas Airlines flight from Adelaide, Australia, to Canberra made an emergency landing at Melbourne late night Monday after passengers heard a loud bang from the back of the plane.

Oxygen masks dropped in the passenger cabin and the plane made a rapid descent. As the plane went from 25,000 feet to 10,000 feet, people were able to breathe normally and take off their masks.

The flight took off from Adelaide on Tuesday at around 6:10 a.m. local time (2:10 p.m. Monday, EST). Due to the depressurization incident, it had to be diverted to Melbourne where it made an emergency landing at around 8 a.m.

Passengers on the flight were “fairly stressed,” according to a passenger Vicky Denny. She said, “There were a few people around me who were fairly stressed and a baby screaming, but it was all very well controlled.”

The pilot was calm and professional but since the passengers weren’t aware of what was happening, they were bound to panic; “They didn’t explain anything as far (as) what was occurring— they said this was an emergency procedure and there was a consistent alert going over the intercom,” Denny told the Adelaide Advertiser.

The passengers were told to remain seated as the flight was making an emergency descent and to keep the oxygen masks on. Later on, Qantas confirmed that the incident was due to an issue with cabin pressurization.

In a statement issued by Qantas Airlines, chief technical pilot Captain Alex Passerini said, “Our pilots and cabin crew handled the incident in line with standard operating procedures. We would like to thank our customers who followed the crew instructions and remained calm during the diversion.”

Passengers were transferred to other flights and the Australian Transport Safety Bureau said it was gathering evidence before a possible investigation. “The ATSB can confirm it has been notified of an occurrence this morning where a Boeing 737 on a flight from Adelaide to Canberra diverted to Melbourne due to reported pressurization issues. The ATSB will gather information into the occurrence before making a decision on whether or not to formally intervene.”

The plane was taken for examination by engineers in Melbourne to determine what the issue was and what caused it.

In the first week of February, a Qantas flight from London to Singapore was forced to turn back to Heathrow Airport soon after it took off. An issue with a cargo door caused the flight to turn back to London, 20 minutes after take-off. Initially the problem was believed to be one of a faulty indicator but after the cargo door hold warning began flashing in the cockpit, the pilot was alerted of a cabin pressure issue, the flight landed in London and passengers were taken to hotels for one night before they were placed in a different flight.