Kansas University student Caleb Bates was making a waffle Saturday night when there was a knock at the door.

“Two guys forced their way in when I answered the door,” he said. “They held guns to my head and basically asked for money.”

The incident in the 1300 block of Tennessee is among several recent violent crimes that spurred KU Public Safety on Wednesday to issue a crime alert to students.

“Lock your doors,” KU Public Safety Capt. Schuyler Bailey said. “Walk in groups. Utilize the various escort services that are available to students.”

Bailey said the office sent out the warning because the events were close to campus.

Bates said he didn’t sense anything was suspicious before he opened the door.

“Right when I saw they had guns, I tried closing the door,” he said. “They told me to get down on the ground.”

The men stole two computer monitors, a DVD player and other items, Bates said.

“One had a gun to my head,” he said. “The other was cleaning out my apartment.”

About 12:15 a.m. Sunday morning, two blocks away, a Lawrence High School student reported that he was beaten and robbed of his wallet and other items. Police are seeking four males in connection with the incident, which occurred in the 1200 block of Louisiana.

And a third violent crime was reported Sunday night, in the same area, the 1200 block of Tennessee.

KU student Fabian Conde said there was a party at his residence Saturday night. And a friend of a friend invited over a group of men. There was a fight.

Conde said the same group returned Sunday.

“They came back on Sunday night and just pretty much let us have it,” he said.

Conde said the group of seven to 10 people walked into the house, broke windows and damaged furniture and other items, and beat up on Conde and others. One was carrying a baseball bat, he said.

“It was pretty bad,” he said. “It was drastic.”

Lawrence Police also are investigating a reported aggravated robbery Tuesday evening at 2600 Compton Square. Several men in their 20s were getting ready to play cards when there was a knock on the door, according to a report.

When one man answered the door, a man entered, showed a gun and demanded money. The victims reported they were told to get on the floor and empty their pockets. Another man walked into the room and began walking around. The men took more than $600 in cash and other items, a report said.One suspect was described as a black male in his early 20s, about 6 feet 1 inch tall, between 180 and 200 pounds, wearing a light blue football jersey and baggy blue jean shorts. The other was described as possibly an American Indian or Hispanic male, in his early 20s, between 5 feet 8 inches and 5 feet 10 inches tall, with a stocky build, wearing a big black T-shirt and long, blue jean shorts.

Lawrence Police said they were investigating all of the incidents separately and it was too early to determine whether they were related.

“We’ll canvass the neighborhoods, work all the leads until we run out of things to follow,” said Lawrence Police spokeswoman Kim Murphree.

KU Public Safety advised students to lock their doors even when home, avoid walking alone and to use escort services such as Jaywalk. They also advised walking only in well-lighted areas and reporting any suspicious activity to authorities.