Two armed robberies were committed around the Yale campus this past week, Yale Police Chief James Perrotti announced in an e-mail to the Yale community on Tuesday evening.

Perotti said the first robbery took place last Wednesday evening in a parking garage at Yale-New Haven Hospital. In a separate incident, a Yale student was robbed early Sunday morning on the way back to his room. Perrotti warned students not to walk alone at night and advised them to use instead the escort service or mini bus.

“As we begin the new semester, I want to remind all members of the Yale community to be aware of personal safety,” Perrotti said in the e-mail. “The incident underscored the need not to be walking alone in the evening, and certainly not in the middle of the night.”

The first incident occurred at approximately 6:30 p.m. Wednesday on the seventh floor of the Air Rights Garage at the hospital, Perrotti said. The robber, who demanded a ride, was armed with a gun and a knife. The employee who was attacked manage to escape with only a cut on her face, and the robber fled by foot.

The second robbery took place around 3 a.m. Sunday as the student walked back to his room from his fraternity. A man in a car stopped next to the student and asked him for money. The robber had a gun, but the student was not hurt, Perrotti said.

The Yale Police Department could not be reached for additional comment Tuesday evening, and it was unclear where the second robbery occurred.

In his e-mail, Perrotti said these incidents highlight why students should be particularly cautious when outside at night. He said that instead of walking alone, students should take advantage of the security services offered by the University. He also encouraged students to call the Yale Police if they see suspicious activity.

Despite the warnings in the e-mail, some students did not react strongly to Perrotti’s message.

A native of Chicago, Ann Peterson ’08 said Perrotti’s e-mail did not alarm her and that she is not any more worried at this time of year than she normally would be.

“Any sizable city is going to have its share of crime,” she said. “[I’m] no expert in seasonal crime patterns, but I don’t feel any less safe during the winter than I do any other time of year.”

YPD Lt. Michael Patten has said that there is usually an increase in crime in the winter because of the earlier nightfall and because people are wearing heavier clothes that better conceal weapons.

But Ashley Gutierrez ’10 said that she has actually become less worried about crime since the beginning of last semester. When she takes the minibus she does so for weather reasons, she said, not for safety reasons.

“Whenever I walk that late I am cautious, but now that it’s second semester I feel more invincible because nothing has happened to me or anyone I know,” she said. “Before, when I got e-mail from the chief it freaked me out, but not this one.”