In what Santa Maria Police Chief Danny Macagni called “the definition of a sad day,” an on-duty police officer accused of having sex with a 17-year-old girl was shot and killed early Saturday morning by a fellow Santa Maria policeman.

The shooting erupted after two of the dead officer’s colleagues tried to arrest him. The accused officer allegedly resisted arrest and fired his handgun, prompting another officer to return the fatal shot.

The officer who was killed was a four-year member of the Santa Maria Police Department with no major disciplinary issues during his tenure, Macagni said during a press conference Saturday afternoon at the Santa Maria Police Station.

“We aggressively investigated this as quickly as we could,” Macagni said. “Who would ever have expected this type of outcome?”

The deadly shooting occurred about 1:20 a.m.

Saturday at McElhaney Avenue and Broadway as police were breaking down a DUI checkpoint they had conducted since Friday evening.

Police supervisors were sent to arrest the officer, who was working at the DUI checkpoint, but he put up a physical fight, Macagni said, and a scuffle ensued.

“He chose to resist, to remove his weapon ... and fire his weapon,” the chief said.

Other officers, including the policeman who fired the fatal shot, came to the aid of the two supervisors making the arrest, Macagni said.

The accused officer was shot once in the chest and was taken to Marian Medical Center for emergency surgery, where he died. No one else was injured.

The police chief did not release the name of either officer involved because family members were still being notified, but he said that information will eventually be made public.

The officer who fired the fatal shot was an eight- or nine-year veteran, Macagni said. As is routine in police-involved shootings, that officer has been placed on paid administrative leave pending the outcome of internal and external investigations.

The Santa Barbara County Sheriff’s Department is investigating the shooting.

About seven officers were on scene clearing up the checkpoint when the shooting happened, and there was very little traffic in the area at the time.

Police were made aware Thursday of some minor misconduct on the part of the accused officer, Macagni said, but explained it wasn’t even serious enough to suspend the officer. Instead, police initiated an investigation, and then the new information came to light.

According to Macagni, information surfaced shortly before the shooting that necessitated the immediate arrest of the officer who was suspected of having an illegal sexual relationship with a 17-year-old girl.

“It was not only compelling, it was egregious and needed to be dealt with immediately,” the police chief said.

“There is some witness intimidation involved,” Macagni added, but declined to reveal further details about the alleged crimes.

It’s devastating when police officers must take any life, Macagni said. While Saturday was a tragic day for law enforcement, he said, illegal activity on the part of public servants can’t be tolerated.

“My officers don’t take that lightly. I don’t take that lightly. It’s tragic anytime it happens.”

He said that while typically the Santa Maria department might call in another agency to handle the arrest of one of its own, it was urgent that the accused officer be arrested immediately to preserve public safety.

 “Who do you call at 1 a.m.?” he asked.

“If you violate the law, I don’t care if you’re wearing a uniform or not,” he said. “The protocol is, as soon as you identify enough information to proceed with a criminal investigation, a criminal arrest, you do so.”

Drew Sugars, spokesman for the Sheriff’s Department, said the agency conducts investigations for other law enforcement departments when it is asked to do so.

He said that while he had no comment right now on the incident, the Sheriff’s Department will eventually submit its findings to the Santa Barbara County District Attorney’s Office.

Saturday’s shooting has struck a nerve with many in the community, including Santa Maria resident Pedro Reyes.

Reyes, vice president of the League of United Latin American Citizens, a civil rights group, showed up to the press conference Saturday afternoon to express his concern about the safety of Santa Maria residents.

After the conference, Reyes said he finds it troublesome that a police officer entrusted with public safety was committing crimes.

“At the end of the day, they are a liability to the city,” he said.

In addition, he wondered if the accused officer’s life could have been spared with other arrest tactics.