Divers are still searching for missing passengers and crew after a sightseeing ship capsized in a squall in Halong Bay, a popular tourist destination in Vietnam, on Saturday.

At least 34 bodies have been recovered and another 11 people have been rescued.

The nationalities of those on board have not yet been stated.

The cockpit and engine room, however, are stuck in mud, making them harder to reach.

“As of now, I am certain there are no more bodies in the passenger cabin,” said diver Đinh Khắc Giông.

“I only worry that some bodies may have drifted outside.”

VN Express reported that the ship, called the Wonder Sea, was caught in a storm around 1.30 pm local time (2.30am ET), which caused it to capsize.

It then lost GPS signal, according to the outlet, which cited the Quang Ninh Provincial People’s Committee.

The navy, border guards, police and port authorities – along with 27 boats and two rescue craft – were mobilised to the scene, VN Express reported, adding that heavy rain and limited visibility due to nightfall were making rescue operations difficult.

Most of the passengers were from the Vietnamese capital Hanoi and traveling as families, according to VN Express, which reported the eldest passenger as 53 and the youngest as just 3.

Over 20 children were on board, VN Express said. Citing the director of a local hospital, the outlet reported that a 10-year-old boy is in stable condition after suffering multiple injuries.

It also reported a 14-year-old boy survived after being trapped inside the ship’s sunken cabin for four hours, citing eyewitness and deputy head of the Ha Long Cruise Ship Association, Bui Cong Hoan.

State broadcaster VTV interviewed a survivor, Dang Thuy Linh, recovering at the provincial hospital.

“I have lost contact with my son, my husband and my friend’s whole family,” Dang told VTV, according to a translation published by Reuters.

“What I am asking now is for everyone to speed up the rescue mission, to save all of them,” Dang added. “Please don’t let anyone behind on that boat. There is so little air left, there is a small chance of surviving.”

The capsize reportedly happened near the Dau Go Cave – one of the largest in the bay.

Halong Bay is a popular tourist hotspot and a UNESCO world heritage site comprising of about 1600 limestone islands and islets.