The college said in a statement Tuesday it would close after receiving new information from law enforcement.
The school was closed Monday after the parents of 19-year-old Jacob Marberger reported he retrieved a firearm and they were unable to reach him.
Officials had initially planned to reopen Tuesday. Classes also were canceled for Wednesday.
The college says it hasn't received direct threats against the campus. The school said arrangements would be made to shelter a small group of remaining students in the community by the end of the day.
The college says an arrest warrant has been issued for the student.
We expect to issue our next update tomorrow. Thank you again to the community for its support! pic.twitter.com/zOCNMfz4EX— Washington College (@washcoll) November 17, 2015
Cheltenham High School, where Marberger was once a student, was put on lockout Monday as a precaution.
Authorities are conducting a high-intensity search.
Marberger is described as a white male standing 5'6" tall and weighing 135 pounds. He has brown hair and brown eyes.
He may be driving a green 1997 Range Rover with Pa. license plate JWY-5876.
Anyone with information is asked to contact the Cheltenham Township Police Department.