The Evanston Police Department evacuated a northbound Chicago Transit Authority Purple Line train Tuesday morning after Chicago police received a bomb threat.

A woman called a Chicago police dispatcher on her cell phone and said she had overheard a Purple Line passenger say he was carrying a bomb, EPD Cmdr. Michael Perry said.

She told police the man said, “I have a bomb and I’m going to blow up the train.”

The train was evacuated at 9:54 a.m., Perry said.

Perry said the woman described the man as being of Arab descent, 6 feet, 190 pounds, with an olive complexion. The man was 30 to 35 years old with black hair, she said. The man wore a dark blue or black canvas jacket, red leather shoes and carried a small red box.

The woman left the Purple Line express train at the Howard station because she was afraid, Perry said. She told police the man remained on the train. When the train stopped at the Foster El stop, Evanston police evacuated the train and questioned 18 passengers.

No one who fit the man’s description was found and none of the passengers questioned recalled a man fitting the provided description, Perry said.

Police said they stopped the train for 10 to 15 minutes to search the cars, but no suspicious packages were discovered, Perry said.

The Chicago Police Department bomb squad is handling the investigation, Perry said.

Despite the bomb threat, Kathryn De Luna, a graduate student in Northwestern’s history department, said she still plans to ride the El.

“Of course it’s worrisome and bothersome,” De Luna said. “But any public place can be a threatening place. That’s part of living in a city.”

Robert Augustin, a CTA customer assistant, said security on El trains is tighter now than at any other time he can remember.

CTA spokeswoman Maria Toscano said security on CTA trains is at a heightened state, but she said she couldn’t divulge specific information about security precautions.

Perry said the bomb threat was the first on an El train in Evanston and one of several threats in Evanston since the Sept. 11 attacks on the World Trade Center in New York and the Pentagon in Washington.

Bank One, 1603 Orrington Ave., closed Sept. 11 after a threatening phone call, Perry said.

Perry said Evanston police have been operating under a state of heightened security since the attacks.

“We’re trying to be more accessible and getting out where people can see us,” he said.