HUPD Chief Francis D. “Bud” Riley sent out a letter on Friday to University offices warning staff of suspicious packages in the wake of the Holyoke threat.

“[HUPD] would like to remind the members of the community to be aware and vigilant about any suspicious activity, whether it be persons, packages or communications,” Riley wrote.

HUPD’s flyers, prepared in conjunction with the FBI and the U.S. postal service inspectors, recommend staff watch out for packages that appear out-of-place, or carry restricted endorsements like “personal,” “private” or “to be opened by addressee only.” Packages with protruding wires, uneven weight packages or return addresses that differ from the postmark city should also be handled with care.

—Staff writer Garrett M. Graff can be reached at ggraff@fas.harvard.edu.