The University of Hawai'i-Manoa issued a campuswide e-mail alert yesterday after a man was overheard on a city bus saying he was planning to shoot 30 students at the university.

A man fitting the description was later seen riding a bicycle near the campus, but left before officials could question him, a UH spokesman said.

The alert did not disrupt classes or other UH activities, said UH spokesman Gregg Takayama.

Police opened a first-degree terroristic threatening investigation but had made no arrest as of 4:30 p.m., East Honolulu District Capt. Robert Green said.

Takayama said a student heard the man making the threats on the bus about noon. The man got off the bus near McCully Street and the student reported the incident to UH campus security and police.

Campus security issued an e-mail alert to all faculty, staff and students about 1 p.m. about a man wearing a camouflage shirt with an American flag on it, khaki shorts and tennis shoes.

Campus security spotted a man fitting the description riding a bicycle on Dole Street toward the Laboratory School about 2 p.m. but could not stop the man. Police and security officers went to the Lab School campus as a precaution to ensure the safety of students leaving at the end of the school day, Takayama said.

Authorities are asking people to report suspicious activity to police at 911 or Campus Security at 956-6911.