A purple banner hung above the entrance way of the 50th Precinct on Kingsbridge Avenue in the Bronx Tuesday to honor NYPD Detective Joseph Lemm, who was killed in a suicide bomb attack in Afghanistan Monday. 

Lemm was among six American troops killed near Bagram Airfield, the largest U.S. military facility in Afghanistan, NATO and Afghan officials said. The Taliban claimed responsibility for the attack.

NYPD Commissioner William Bratton said in a statement, "Detective Joseph Lemm epitomized the selflessness we can only strive for: putting his country and city first."

Lemm was part of the 105th U.S. National Air Guard based out of Stewart Airforce Base in Newburgh. He was a 15-year veteran of the NYPD and promoted to detective in January 2014, serving in the Bronx Warrant Squad.

Gov. Andrew Cuomo has ordered flags lowered to half-staff at federal, state and county buildings throughout New York.

While a member of the NYPD, Lemm deployed three times -- twice to Afghanistan and once to Iraq. Capt. William Kivlehan said Sgt. Lemm was "a cop who got a lot of violent guys off the streets." 

Lemm's body will be flown from Afghanistan to Dover, Delaware for an initial internment service and then to New York where his family will plan a proper burial.