Police have faced off against armed suspects in North Philadelphia in the last two days, with one man critically injured during a daylight shooting today while the other - wearing a bullet-proof vest - was wrestled to the floor of a crowded SEPTA bus.

In the bus incident, a 35th District officer and the gunman desperately fought for a fully loaded semi-automatic that fell to the ground.

"This officer was fighting for his life and for the lives of everyone on that bus," said Deputy Commissioner Richard Ross. "This guy was not willing to go, and God knows what he was going to do if he got that gun."

The drama unfolded yesterday morning at North Broad and 66th Streets, less than a block from the Dunkin' Donuts where Officer Chuck Cassidy was fatally shot Oct. 31 while making routine checks of local businesses. Cassidy was shot in the head as he interrupted a robbery in progress. He was one of three officers who have been fatally shot during robberies in the city within two years.

"It speaks to the dangers our officers are confronted with each and every day," Ross said. "It's sometimes hard to get a grasp on exactly how violent some of the people in this city are."

The melee began after a passenger got off the bus about 8:30 a.m. and handed the driver a note that said that a man seated in the rear, wearing a blue shirt and jeans and with braided hair, had a gun.

Shortly afterward, the officer, who was not identified, was flagged down by a man concerned about a passenger with a gun on the K bus.

As the officer boarded and then walked toward the rear of the bus, which was still stopped, the man stood to exit the back door - and reached into his waistband, police said.

The officer wrestled with the man and reached for the man's gun, which fell to the floor. The two combatants then rolled down the rear steps of the bus.

The officer yelled for the driver to grab the gun, and other officers arrived to assist.

Sorrell Groves, 27, of the 5100 block of Whitby Street, was charged with attempted murder, aggravated assault and related offenses.

After he was subdued, police quickly learned that he was s wearing a bulletproof vest with a trauma plate over his chest. The handgun had a bullet in the chamber and 13 rounds in a magazine. The serial number, police said, was obliterated.

"He was in a heck of a struggle," Ross said of the officer. Ross said he called him to offer congratulations for exercising restraint in a situation that could have turned fatal.

Today's incident, meanwhile, began about 12:30 p.m. when a driver reported that he was confronted at gunpoint by a man in his 30s who stole his late-1990s Buick Le Sabre, said Lt. Frank Vanore of the Public Affairs Unit.

A Highway Patrol officer spotted the vehicle nearby and pulled the vehicle over at 30th Street and Lehigh Avenue, where the driver fled on foot, Vanore said. During the chase, Vanore said, the man turned toward the officer with the gun and the officer shot him.

The man was taken to Temple University Hospital in critical condition and was expected to survive, Vanore said.

This year, police have reported 39 gun discharges, including 20 shootings involving civilians, seven that have been fatal. That also includes 17 shootings involving dogs and two accidental shootings, police said.

Police Commissioner Charles Ramsey, who was appointed by Mayor Nutter in January, has instituted additional training for officers on the use of lethal force while a thorough review of the department's policy is being conducted.

Last year, 15 fatal police shootings were recorded. In 2006, there were 20 fatalities, the most since 1980.