Three people from Oklahoma — including a University of Oklahoma student who has been temporarily suspended — were responsible for racist messages sent to some black freshmen at the University of Pennsylvania on Friday, school officials said Sunday.

Some students shared screen shots of pages from GroupMe, a social media group messaging account, which included a photo of people hanging from a tree, slurs and a “daily lynching” calendar.

The messages were sent at a time when racial tensions have been particularly raw on campuses nationwide, after protests last year over bias and police violence, and intense reactions to the presidential election last week.

A criminal investigation has concluded that no University of Pennsylvania students were involved, according to the message from the university.

The messages, which left some students in tears, frightened and angry, led to protests, according to the campus newspaper the Daily Pennsylvanian, which first reported the story.

Two student leaders did not immediately return requests for comment Sunday evening.

Amy Gutmann, the president of the University of Pennsylvania, and other leaders sent a message to campus Sunday:

… the criminal investigation has concluded and there are no Penn students associated with the issuance of these racist posts on GroupMe.
The three individuals who have been linked to the GroupMe message that was sent to first-year Black students here at Penn reside in the state of Oklahoma. As we reported to you early Saturday morning, one of those students attends the University of Oklahoma and has been suspended from the University as they complete their internal investigation.
Second, our primary concern remains with the students who were the recipients of this dreadful hatred. Many Penn staff members are working with them to be sure that they are receiving all the support that they need. We communicated with all deans earlier today (Sunday) advising them to ensure that faculty are sensitive and responsive to the academic needs of any and all students who are impacted by this absolutely awful incident.
Finally, we call on everyone to recognize that the events of the past few days are a tragic reminder of the overt and reprehensible racism that continues to exist within some segments of our society, and that we all need to unite together as a community and a society to oppose.
We are deeply saddened that Penn students were the victims of this hate, to which absolutely nobody should be subjected. Penn Police continue to work with the FBI and law enforcement in Oklahoma, and our hope is that the full investigation into this terrible incident will be concluded shortly. We will continue the work of healing with members of our community.

David Boren, the president of the University of Oklahoma, announced Friday night that a student had been temporarily suspended, and said it appeared that the problem did not originate at OU, but started elsewhere. He said, “The University of Oklahoma has made it clear that we will not tolerate racism or hate speech that constitutes a threat to our campus or others. We have a record of taking swift action once all of the facts are known.”

In 2015, a video of OU students going to a fraternity event chanting a racist song that included a reference to lynching went viral.