It was getting to be stifling hot in the Metrorail cars stuck between Prince George’s Plaza and College Park on Tuesday night. With no power on the Green Line train, there was no air conditioning.

And even more upsetting, there seemed to be no plan to get passengers off the train.

Joan Bisset, who was on the Greenbelt-bound train, said that for more than 15 minutes after the train stalled, passengers were left without a clue as to when help might arrive. The driver said she was not permitted to open the doors to let them out. So 150 hot, angry riders took matters into their own hands.

Pushing open car doors, they clambered off the train and stepped onto the tracks several feet below.

“I sat on my rear end and asked a man ahead of me to hold my hand,” recounted Bisset, who was on her way home when the train got stuck shortly after 6 p.m.

The “self-evacuation,” as Metro calls such acts, was not safe for the passengers, said spokesman Dan Stessel, who added that Metro strongly discourages such action.

The outside temperature was still in the 90s.

“I am sure it was very uncomfortable,” Stessel said. But, he added, the risk outside the train, where tracks are electrified, can be very high.

A rescue train was en route. But once passengers had dropped to the tracks and were walking toward College Park, Metro had to cut power to the inbound and the outbound tracks, causing further delays along the Green Line, he said.

One passenger was treated for a sprained ankle.

Another 150 or so passengers who remained on the train were escorted off by Metro police and other personnel.

Service was restored on the Green Line by about 8:30 p.m.

That was little consolation to Bisset, the chief operating officer of Soujourners, a social-action foundation based in Columbia Heights.

“There wasn’t a plan. People were on the train for a long time with no information,” she said Wednesday.

Bisset said that after waiting and waiting aboard the train, she called 911. Fire and rescue workers soon arrived. But still, no sign of a rescue train.

And the emergency personnel did not supply the hot travelers with water, something Bisset said they should consider in the future.

As for Metrorail, she said, “you would think that within 15 minutes they know how to evacuate the cars.”

Bisset made it to the College Park station, where she boarded a commuter bus home to Laurel. Later that night, she and her husband drove to Greenbelt, where she had parked her car Tuesday morning before heading for work.

It was dark. She walked a few steps and stumbled in a depression in the pavement.

“I fell flat,” she said. “I started to cry. And I am not a teary woman.”