A teenager was arrested in two sexual assault-related crimes in different parts of the District over the past two weeks, including one in which he allegedly attacked a teenage girl in a dorm room at Howard University, District police announced Saturday.

Police have charged Demarco Myles, 19, of Northwest with assault with the intent to commit first-degree sexual assault while armed in an alleged stabbing on Oct. 26 in Northeast.

He was also charged with first-degree sexual assault while armed in Friday’s alleged attack on the Howard student.

The attacks occurred in the afternoon one week apart.

In Friday’s incident, in a Howard dorm room in the 2200 block of Fourth Street NW, the attacker displayed a knife, according to police, and sexually assaulted the 19-year-old student.

In the October assault, a woman began to open her apartment door in the 2300 block of Washington Place in Northeast when the attacker forced his way through, police say.

The victim fought the attacker off while he tried to sexually assault her, and he stabbed her multiple times, police said.

At a brief news conference, Lt. Vendette Parker would not say how the attacker gained access to the Howard dorm. She said the attacker had “extremely violent, predatory tendencies.”

“Had we not located [the suspect], it is our belief that he would have continued to attack women,” Police Chief Cathy L. Lanier said in a statement.

Myles was arrested in the 5300 block of Fourth Street NW without incident.

Kerry-Ann Hamilton, a Howard spokeswoman, said university officials found Friday’s incident “very troubling.”

The university is ramping up 24-hour security at its dorms. The school is also providing counseling services and working with various departments as officials conduct an internal investigation, she said.

Officials are asking students to be aware of their surroundings and to notify police of anything suspicious.