Two detectives injured in a gun battle this morning in the Bronx had to undergo an alcohol breath test to make sure they were fit for duty at the time, police officials said today.

The shootout set the stage for another battle between the police department and unions over a new alcohol testing policy for police officers that fire their guns at someone. Today was the first time the policy was implemented after it went into effect on Sunday.

Police said three detectives returned fire when a suspect began shooting at them at around 5:30 a.m., and later submitted to a breath test by Internal Affairs Bureau officers.

Police Commissioner Raymond Kelly introduced the policy this summer in response to the shooting of Sean Bell last year in Queens, who was killed in a hail of 50 police bullets.

Unions had already prepared to challenge the new policy before the shooting this morning outside a Webster Avenue apartment building. The president of the Detectives Endowment Association, Michael Palladino, said he would try to use the case of the two detectives in a federal court challenge to the policy.

“They put their life on the line, they got injured, they were shot at it. It’s degrading and it’s demoralizing to have these officers have to undergo a Breathalyzer,” Mr. Palladino said, referring to a name brand of the alcohol test.

The officers, Detectives William Gonzalez and Daniel Rivera, both with nearly 20 years on the force, sustained minor gun wounds while pursuing a suspect from a July bodega shooting, Mayor Bloomberg and Police Commissioner Raymond Kelly said at a news conference this morning.

Cornered in an alleyway behind a Webster Avenue apartment building, the suspect, identified as Jermaine Taylor, 20, fired at least six shots with a 9-mm Italian semi-automatic pistol, officials said. Police fired 13 shots.

Officials said the shooting was justified under official police guidelines.