Police say robber asks to use phone, then punches victims in the face.
California police are asking for the public's help to find a man believed responsible for at least two violent cellphone robberies at Cal Poly Pomona.
The attacks sparked fear among students, prompting some students to change the way they get around campus.
"It kind of scares me because he could steal my cell phone and it's kind of expensive. It has everything on it," said student Trista Demuth, who now drives to all of her classes.
Police released a composite sketch of the of the suspect: a white man in his 20s, about 5-foot-9, with a thin build and blond hair.
"He hasn't used any weapons, this is strong-armed robberies so we're encouraging our campus community to keep their eyes peeled," said Cal Poly Spokeswoman Uyen Mai.
The first incident happened April 30, when a white male in his early 20s asked to use a student's cell phone, then punched him in the face and ran away.
The second incident happened May 3, when a male approached a student who was walking through a student parking lot.
"After demanding to see the student's phone, the man punched him in the face, took the cell phone and ran," campus officials reported.
University police are warning students, faculty and staff "to be aware of their surroundings and report any suspicious-looking people or situations immediately."
"With the smart phones they're just becoming more expensive and with most providers going, they're easily unlocked," said student Jeremy Schiff.