Hong Kong police have arrested two technicians following Saturday’s Langham Place escalator

accident that resulted in 18 people being injured.

Two persons are still in hospital in a stable condition. One, a 47-year-old man, was the most seriously injured when the escalator suddenly reversed on Saturday.

Arrested for allegedly attempting to pervert the course of justice, the two technicians, aged 22 and 52 years, have been released on bail.

A damaged driving chain is thought to have caused the incident, and a braking device also malfunctioned, according to Hong Kong’s Electrical and Mechanical Services Department.

Shoppers at Langham Place lost their balance and fell as the 45m escalator suddenly reversed direction. More than 10 people piled up near the base of the escalator, a witness says.

A woman whose leg was injured in the incident says the escalator was moving twice as fast as usual, the The Straits Times reports.

A Langham Place spokesman says the escalator had passed a biannual safety inspection just two days before the incident. Installed by Otis Elevator, it links the fourth and eighth floors of the Mong Kok shopping mall on Argyle Street, and is one of the longest indoor escalators in Hong Kong.

Langham Place began inspections of all its 40 escalators on Saturday night, with the escalators still ­cordoned off yesterday.

Escalator engineer Charles Wong Kai-hon says most escalators have a “non-reverse ­device” that can signal auxiliary brakes to kick in, reports the South China Morning Post.

“If the main brake cannot stop the escalator going into reverse, the non-reverse device should have sensed it and given a signal to the auxiliary brake,” says Wong, a member of the Lift and Escalator Safety Advisory Committee. “In this case it didn’t, and this will need to be investigated.”

An Otis spokesman says the arrest of the technicians came as “a surprise” and the company will defend them. “Our legal team is working with law enforcement to clarify the situation.”

Meanwhile, the government has ordered contractors to test 57 escalators more than 15 metres in height within a month.