Three teenagers were charged yesterday after allegedly punching a pregnant woman in the stomach and demanding a man's car keys at gunpoint in Brooklyn Park.

Like three other incidents in the string of attacks, police said yesterday's 4 a.m. carjacking attempt was violent - and botched.

Two men and a pregnant woman were getting out of a vehicle in the 300 block of Arden Road when an armed man pointed a handgun at the group and demanded their car keys. One of the men punched the pregnant woman in her stomach, while another held a gun to her friend's head after he refused to hand the keys over.

The teens gave up and ran after the woman told them the car they were after is equipped with an electronic tracking device designed to locate stolen vehicles, police said.

Officers fanned out in the area in search for the teens, and in the process, happened upon a blue Toyota Yaris that had been carjacked from a woman on the same block Saturday night. The teens were found nearby shortly after, and ran away once they saw police.

The foot chase continued for several minutes before police caught up with all three teens and arrested them. While searching one of the teenagers, officers found keys in his pocket that were stolen Saturday night to start the Toyota Yaris.

The victims in yesterday's robbery identified all three teenagers, and police recovered the handgun.

"It's brazen of them to commit such a crime," said Sgt. John Gilmer, a county police spokesman. "Our officers in the field did an excellent job of apprehending them as quickly as they did and they should definitely be commended."

Police charged Rashad Tyree Knight, 18, of the 6400 block of Freedom Drive in Glen Burnie, Rashard Anton Watkins, 17, of Baltimore and Travis Jawan, 17, of Baltimore with attempted robbery, assault, armed carjacking and handgun violations in connection with yesterday's robbery.

Charges are pending in Saturday's carjacking.

On that morning, a woman told police she was leaving her car on the 300 block of Arden Road West about 12:30 a.m. when two black teenagers wearing white tank tops and dark-colored pants approached her in the alley behind her house.

One of the teens brandished a silver handgun as he threw the woman up against a vehicle and demanded her purse.

When she told him she did not have a purse, the teenagers reached into her pocket and took her cell phone and keys.

They then got into her blue 2007 Toyota Yaris and drove away, police said.

That carjacking came just two days after three people were charged with two back-to-back carjacking attempts in Glen Burnie and Pasadena.

At 10:48 p.m. Thursday, a 39-year-old woman was walking from her vehicle to her home at the Americana Southdale Apartments on Americana Circle in Glen Burnie when a woman pointed a handgun at her and demanded her car keys.

Before she could hand them over, a witness started screaming and scared the woman away. The woman ran empty-handed to a waiting silver Dodge Stratus.

Ten minutes later, police got a call for a second carjacking attempt just over a mile away at Marley Run Apartments in Pasadena.

Tony Hopkins, 25, was walking to his apartment with this father, Tony Sr., when a man pointed a gun at him and told him to hand over his car keys. The younger Mr. Hopkins kept and eye on his attacker, and when the man turned the gun to his father, he punched him in the face and took the gun. The man, and another man waiting downstairs, ran to a waiting silver Dodge Stratus and drove off, police said.

A man saw what happened and went after the vehicle. He called police and relayed his location until officers caught up with the car and made three arrests. Ashley Cully, 19, of Melrob Court in Annapolis, was charged with attempted carjacking, attempted armed robbery, attempted armed carjacking and other related offenses in connection with the first incident on Americana Circle. Ms. Cully, along with Darryl Z. Moore, 27, of Conley Drive in Annapolis, and Rico D. Thomas, 22, of Hammarlee Road in Glen Burnie, were each charged with attempted robbery, attempted armed robbery, attempted carjacking, attempted armed carjacking, first-and second-degree assault, and use of a handgun while committing a violent felony regarding the attack on Elmberry Court.

Lt. Eric Hodge, a police spokesman, said four carjacking attempts in one week is out of the ordinary for the county and the incidents are most likely coincidental.

"We don't usually get this many in a week," he said. "But, I think this is probably just an anomaly."

Though arrests have been made in all four attacks, police are warning residents to take extra precautions when walking to and from their vehicles, especially during night and early morning hours.