HONG KONG (Reuters) - With all other escape routes blocked, some of the remaining protesters holed up in a Hong Kong university tried the unthinkable: they crawled through the sewers to get out.

FILE PHOTO: Anti-government protesters look inside a sewer as they look for an escape route in an underground carpark at the Hong Kong Polytechnic University (PolyU) in Hong Kong, China, November 20, 2019. REUTERS/Adnan Abidi

How many took to the underground network of tunnels to flee and whether any actually got away is unclear.

But for those who tried, it was an experience they were unlikely to forget.

“I never thought that one day I would need to hide in a sewer or escape through sewers to survive,” student Bowie told Reuters.

“I’ve never thought I would live like that ... The most unforgettable feeling is the fear when I was inside.”

The 21-year-old said that she and others had tried various ways to flee the campus besieged by police, but none of them made it out.

“This time we truly think we need to fight, or we die, so we went into the sewer.”

Bowie was one of a few dozen people still trapped in the Hong Kong Polytechnic University this week.

After two days of some of the most intense clashes since anti-government protests began in the city 5 months ago, police have barricaded the streets around the campus and are waiting for activists to surrender. [L3N2800OG]

Fearing arrest on rioting charges that could bring years in prison, small groups of protesters waited for low tide before pulling up the gratings and heading down into the unknown.

At times they were brushing off cockroaches, even as they heard police cursing them and calling them cockroaches from the streets above.

Authorities, wise to the attempts, moved to thwart them.

Fire service divers sealed off the entrance to the sewers within the university, while others searched for anyone trapped, injured or dead.

A local police commander said on Wednesday night that they had arrested two men climbing out of a sewer in a nearby street. They also arrested three other men and a woman who had removed a manhole cover to help them surface.

Those trying to flee via sewers took torches, rope, first aid kits and water and tried to use weak phone signals to track their progress. Some groups also carried spray cans - marking the tunnels for other groups.

“The distance looks short above ground but time becomes slow downstairs,” said another tunneller, Sun, 22, a part time clerk.

Bowie described smelling the stench, seeing snakes in the tunnel and battling her fears about water levels rising with the tide.

She said that her group, worried about running into police when they emerged, spent an hour swimming before they found a spot to rest and take stock.

They decided to find the nearest exit, thinking they were already clear of the campus.

“When we reached the exit, we found we were still in Poly,” she said. “We were very disappointed.”