Sexual assault on Esplanade reported

At 2:52 a.m., a man who attends a Boston-area university called police from the intersection of Commonwealth Avenue and Deerfield Street, said Jake Wark, a spokesman for the Suffolk district attorney.

The man said he had come across a woman on the Esplanade who was soaking wet. He said the woman, whom he did not know, told him she had been sexually assaulted and thrown into the Charles River.

The woman then departed but left her purse behind. Authorities used the contents of the purse to find the residence of the woman, who attends college in Boston. When officers went to the woman’s residence, she refused medical attention and did not want to identify the person she said assaulted her.

Wark said he could not say why she declined to describe the person.

“That’s her decision,’’ he said.

Authorities are not releasing the name of the woman or the university she attends, Wark said.

Police are trying to determine if this report is connected to sexual assaults that have occurred over the summer in recent years.

In June 2007, a woman was raped while jogging near the Massachusetts Avenue bridge on the Esplanade late at night. Similar attacks occurred on the Esplanade in July 2007, and in July 2009. All three victims gave similar descriptions of their attacker.

Authorities believe that man might also be responsible for the rape of a 30-year-old woman that occurred in South Boston near Joe Moakley Park in July 2006.

The victims in all of those cases described their assailants as a bald black man with a medium build in his mid-20s to mid-30s, about 5 feet 8 inches to 5 feet 10 inches.

Last April, a woman was sexually assaulted while sitting on a park bench on the Esplanade.

She said the man attacked her after engaging her in a “lengthy conversation,’’ police said.

Police are warning residents to take extra care when spending time in public areas at night by carrying a cellphone, staying in well-lit areas, traveling with friends, and avoiding one-on-one contact with strangers.

Martine Powers can be reached at mpowers@globe.com.