A 45-year-old employee of Boston's Northeastern University was injured on Tuesday when a package delivered to the school exploded while he was handling it, police said, adding that a second package was found and rendered safe.
Police did not reveal how the packages were delivered to the urban campus.
The injured person was taken to a hospital for treatment to his hands, Boston police Superintendent Felipe Colon told a news conference.
"A search revealed a second similar package that was ultimately rendered safe by our bomb squad. I will tell you that the scene is secure in that the investigation is ongoing," Colon said.
The police bomb squad, the Boston Fire Department and Boston Emergency Medical Service were among those investigating the incident, police said.
Evening classes were canceled in six buildings, campus police said on Twitter.
Police at other Boston-area campuses including Harvard University and the Massachusetts Institute of Technology urged people to be cautious and asked them to report any suspicious packages.
The city was rocked by the Boston Marathon bombings of 2013, when three people were killed and more than 260 others wounded by a pair of homemade bombs at the annual race.
In 2015, a jury convicted Dzhokhar Tsarnaev and sentenced him to death for helping carry out the attacks along with his older brother Tamerlan, who died several days after the bombings in a gunfight with police. The gunfight ended when Dzhokhar ran his brother over with a stolen car as he fled the scene. He was captured a day later. (Reporting by Daniel Trotta; Editing by Scott Malone and Raju Gopalakrishnan)