London ? More than 2,000 people were stranded beneath the English Channel for up to 16 hours when their Eurostar trains came to a halt in a tunnel, leaving many of them without food, water — or any idea of what was happening.

In the end, they all emerged safe on Friday night, but some suffered claustrophobia or panic attacks, and many passengers complained that Eurostar staff members had done little to help them through the ordeal, which forced some to walk part of the dark tunnel, 24 miles of which is under water.

Eurostar’s executives have offered apologies, refunds, free travel and more, but the company has canceled all passenger services through the Channel Tunnel until Monday in a bid to figure out what happened.

“It was just pandemonium,” said Lee Godfrey, who was returning to London from Disneyland Paris with his family when it was caught in the tunnel. He said people suffered asthma attacks and fainted after the train’s power went out, cutting off light and air vents.

“People were very, very panicky,” he told BBC radio, complaining of poor communication and saying that some passengers had to open the emergency doors themselves.

Godfrey’s was one of four trains that were stuck in the tunnel Friday evening for reasons that remain unclear.

Eurostar officials have speculated that the quick transition from the icy cold of France, which is suffering some of its worst winter weather in years, to the relative warmth of the tunnel could have interfered with the trains’ electrical systems. But the company’s chief operating officer, Nicolas Petrovic, said Eurostar will have to investigate why the trains broke down.

“We’ve never seen anything like that at Eurostar,” Petrovic told France-Info radio on Saturday.

The company has canceled regularly scheduled services until Monday for test runs.

“We don’t want a repeat of last night,” Eurostar spokesman Paul Gorman said.

Some passengers were evacuated by being taken through the darkened train tunnel onto shuttles. Others were left aboard two trains that were linked together and pushed to London by smaller diesel trains.