Post-Gazette -- A Pennsylvania Army National Guard soldier from Butler was killed by a suicide bomber in Iraq on Sunday, one of 18 American fatalities over the past week in a surge of attacks that also has killed scores of Iraqis.

Sgt. Carl Morgain, 40, was manning the machine gun in the turret of his Humvee in a suburb of Tikrit, the hometown of deposed Iraqi President Saddam Hussein, when a vehicle with taxi markings approached and exploded. Three other Western Pennsylvania guardsmen and four Iraqi policemen were slightly wounded in the attack.

The recent rise in fatalities among U.S. troops is raising concerns that the insurgents, who are largely Sunni, may again be focusing their sights on U.S. forces in addition to rival Shiites, who now control the country.

The deaths come as the U.S. military is trying to arrange a graceful exit from Iraq by giving more responsibility to indigenous security forces. But with the Iraqi security services still relatively weak, U.S. troops remain in the line of fire, targeted by insurgents who have shown an increasing ability to attack when and where they please.

More than 620 people, including 58 U.S. troops, have been killed since April 28, when insurgents launched a bloody campaign after Prime Minister Ibrahim Jaafari announced creation of a new Shiite-dominated government.

In the northern city of Tal Afar yesterday, there were reports that militants were in control, and that Shiites and Sunnis were fighting in the streets, a day after two car bombs killed at least 20 people. Police Capt. Ahmed Hashem Taki told the Associated Press that Tal Afar was experiencing "civil war." Journalists were blocked from entering the city of 200,000.

Morgain -- a member of A Company, 112th Infantry, which is based in Butler -- was the fourth Pennsylvania Army National Guard member to die in Iraq. The company is part of Task Force Dragoon, a battalion-sized Pennsylvania guard unit that has been in Iraq since December. It is based near Tikrit.

Morgain's team and that from another Humvee were providing security for a routine visit to the police station when the attack occurred, said Lt. Col. Chris Cleaver, public affairs officer for the Pennsylvania National Guard.

Morgain was watching a suspicious vehicle when the taxi approached from behind. Morgain was drawing his sidearm to ward off the taxi when the bomb detonated, Cleaver said.

The other soldiers injured in the blast were Staff Sgt. Steven Kerr, 35, of Bradford; Spc. Matthew Sweigart, 24, of Mechanicsburg, and Staff Sgt. John Williams II, 43, also of Mechanicsburg.

Williams was driving the Humvee but was protected from the blast by the vehicle's armor. Sweigart and Kerr had dismounted but were far enough away that they sustained only minor injuries.

Morgain joined the Army in 1982 and was trained as a microwave communications technician. He served for a time at Camp David, the White House's retreat in rural Maryland, providing communications for the president.

Morgain joined the Pennsylvania Army National Guard in 2000. Originally assigned to A Company as a communications technician, he converted to infantry.

"He missed it. He loved being a soldier. He graduated first in his class as an 11B [infantry]," said Sgt. 1st Class John Mahler.

Military certificates and a cherished picture taken at Camp David with former President Ronald Reagan adorn the walls of Morgain's home, said Maj. Bruce Farrell, chaplain for the Pennsylvania National Guard. "His home is full of emblems of his love for his nation and his love for the Army," Farrell said.

Morgain's wife, the former Janice Elaine Stanky, 40, along with the wife of another sergeant, last June formed Support Operation Soldier, a Butler-area charity that each month sends "care packages" of toilet paper, snack foods and DVDs to Pennsylvania soldiers deployed to Iraq. "We don't want people to forget we're over there," Janice Morgain said in an interview in January.

Carl Morgain also is survived by his daughter, Madison Marie Morgain, 12; his stepson, Zachary Taylor Macurak, 17; and his mother, Carol Fay Morgain.

A trust fund for the Morgain family has been set up at First National City Bank of Pennsylvania. Funeral arrangements have not yet been made.

"He was a great soldier and will be missed by all of us here," said Task Force Dragoon's commander, Lt. Col. Philip Logan. "We will honor his memory by continuing the fight."

Click here to visit an online site created to honor the memories and sacrifice of Sgt. Morgain and the other American service members lost in Afghanistan and Iraq. More than 19,000 visitors have already posted tributes to the fallen in the online guest books provided, with more expected as Memorial Day approaches.