LONDON -- Train passengers got trapped inside a London station after staff locked up and went home early in the snow.

The 30 commuters were forced to climb through a window in Streatham Hill train station in the early hours of Sunday in order to leave the building, the Streatham Guardian reported Tuesday.

Passenger Tom Neenan said that when passengers arrived at the south London station, it appeared closed, and the gates allowing them to leave were locked.

"Somebody managed to shimmy open the window," he said. "Luckily, the window opened fairly easily. But it was quite annoying, really."

Train provider Southern apologized for the incident and said that an agency staff member accidentally closed the station before the last train departed.

"We staff our London stations from the first to the last service, and on this occasion, it appears the agency staff member went off duty before the last train departed from the station," a spokesman said. "We are investigating with ... the agency that provided the staff member why their employee did not follow the correct procedure for closing down the station."