The United States is in close contact with its Philippine partners and stands with Filipinos in rejecting the act of violence, it said in a statement.
"We continue patrols and security in schools is tighter," Major Alinaid Moner, spokesperson of the Lanao del Sur police office, told News5 radio station on Monday.
Mindanao State University (MSU) is continuing operations as it is the period for final exams, Moner said.
Philippines President Ferdinand Marcos Jr and security officials said on Sunday the crime was perpetrated by "foreign terrorists".
Hours after, the Islamic State claimed responsibility for the bombing at the MSU gymnasium located in the southern city of Marawi, which was besieged by Islamist militants for five months in 2017.