A Metro spokesman said 500 to 600 passengers were evacuated from the train and transferred to buses. (Jonathan O'Connell/The Washington Post)

A train carrying hundreds of passengers lost power inside a Metro tunnel Tuesday evening and was stuck for more than an hour before rescuers got them out, Metro officials said.

More than 250 people were on the Green Line train, fire department spokesman Tim Wilson said. Metro spokesman Dan Stessel said it appeared that no one was injured in the incident, near the Georgia Avenue-Petworth station in the District, though a woman was seen on a stretcher outside the station.

The third rail, which powers the trains, lost electricity shortly before 6 p.m., but hours later it was still unclear why it happened, said Metro spokeswoman Morgan Dye. She added that everyone had to be removed from the train before Metro could investigate the problem.

At about 11 p.m., train service on the Green and Yellow lines was fully restored, according to a tweet from Metro officials, and the Columbia Heights and Georgia Avenue stations were reopened.

Stessel said fire and emergency medical personnel evaluated every passenger on the train to see whether anyone needed medical attention. Once the passengers were off the train, they were transferred to several buses outside the station.

Riders on the northbound Green Line train said it came to a sudden stop in the tunnel, about 100 feet from the platform at the Georgia Avenue station. The train’s lights and air conditioning went out, and the conductor announced that the train had lost power.

“There was no smoke. It was hot, but for the most part, people were okay,” said Boubacar Hanes, who was on the train.

Passengers said a few people did not wait for rescuers; they walked out through the tunnel on their own.

Lauren Kiesler, who lives in the Adams Morgan neighborhood, said she was heading to visit a friend in College Park. Children were crying, and a pregnant woman had to go to the bathroom, she said.

Earlier, service between U Street and Fort Totten, a busy portion of the Green and Yellow lines, was suspended because of the power problem.

Julie Zauzmer contributed to this report.