Yale Police Department Chief Ronnell Higgins admitted his department is “concerned” after the fourth mugging on or near campus in the past week.

An undergraduate was nearly robbed on the corner of Prospect and Grove Streets at 10:20 p.m. Tuesday, Higgins said in an e-mail to the Yale community Wednesday morning. A man approached the student and demanded the student’s bag, before a witness yelled and the robber fled, Higgins said, adding that no injuries were reported.

“We’re taking action, we’re out on campus and in the surrounding areas with increased patrols,” he said in an e-mail to the News Wednesday evening.

Those in the Yale community can aid the YPD’s efforts by not walking alone after dark, using the shuttle or security escorts and being aware of their surroundings, Higgins went on to write.

Monday’s attempted robbery comes on the heels of two Saturday evening robberies, both of which took place within three blocks of Pierson College, and an attempted robbery on Monday near Prospect and Edwards Streets. After those muggings, Associate Vice President for Administration Janet Lindner said the YPD would deploy more officers around campus based on crime data.

CORRECTION: Oct. 13, 2011

An earlier version of this article misstated the date on which a robbery occurred at the corner of Prospect and Grove Streets.