As police have stepped up patrols around Georgia Tech following a Sunday morning home invasion and robbery inside a dorm room, students told The Atlanta Journal-Constitution what could have prevented the break-in.

"These doors stay unlocked when they close, unless you lock them yourself," said senior and North Avenue Apartments resident Nick Forman.

Kathy Chang said she has friends who live across the hall from the victim who was robbed early Sunday morning and is worried for them.

"I was kind of scared for them because they had their door unlocked," Chang said.

Around 1 a.m. Sunday, a 20-year-old student awoke to find two men in his room stealing his laptop, cell phone and wallet, campus police said.

"Move, and I'll shoot you dead," one of the men told the victim at gunpoint, according to police reports.

Both suspects were described as black men in their late teens or early 20s. One, with the handgun, was wearing a white t-shirt and red basketball shorts. The second suspect had short dreadlocks, a black hat, khaki tan shorts and a black backpack.

Georgia Tech Deputy Police Chief Robert Connolly said police are encouraging students staying on campus to lock their doors, "even if they're just going down the hall."

Connolly noted that in the summer months, there are "less eyes to report suspicious activity."

But students said they were baffled how one, let alone two, individuals were able to get into a residential complex that uses gated revolving doors that allow only one person to enter at a time, to prevent doors from being errantly left ajar. There also are thick metal garage doors on driver entrances to the parking garages.

"I don't know how they got two people in," Forman said.

Sunday's robbery, police said, capped a two-week period of hold-ups around the Tech campus. Between June 21 and June 23, five robberies were reported by people walking along streets near the university.

In each of the incidents, victims told police a pair of suspects ran up on them, produced a gun and made off with valuables like computers, mobile phones or credit cards, according to Atlanta police reports.

"They seem to be approaching the victims from the rear," Atlanta police Lt. Jeff Cantin said. "And they're running to a vehicle of some kind to make their escape."

Investigators used surveillance cameras and victim descriptions to identify two possible getaway vehicles -- a gold or tan late model Chevrolet Malibu and a white Jeep Cherokee.

Police also found video of one of the possible bandits as he entered a 10th Avenue convenience store to use one of the robbery victim's stolen credit cards at an ATM, Cantin said.

Though at least one of the pedestrian robbery incidents reported a student's dorm access card being among the items stolen, police have stopped short of linking the street robberies with Sunday's incident.

"We're not at the point of saying they're connected," Connolly said. "Even if there are statements that are similar."

Police are combatting the string of robberies, the result of a seeming cycle they said finds increased crime in June and July, by increasing visibility around campus and availing themselves to concerned parents.

"[Tech] gave us five more officers in recent months," Connolly said. "And when this happened Sunday, we had everyone answering phones, telling parents what we were doing to solve the issue."

Atlanta and Georgia Tech police are working together to investigate the crimes. They are asking students and residents of the campus community and nearby Home Park to remain vigilant and put off texting or reading mobile devices while walking around the area.

"Pay attention to your surroundings," Cantin said. "And when you can, use some of the campus resources [like van service]."

Police ask that anyone with information about any of the robberies call Crime Stoppers Atlanta at 404-577-8477. Anonymous tips are accepted, and rewards are available for any information leading to an arrest or prosecution.

— Staff writer Fran Jeffries contributed to this article.