In less than a month, three pedestrians have been hit and killed by Houston police officers responding to calls.

The most recent happened shortly after midnight on Tuesday, Jan. 17, according to the Houston Police Department.

Officers were heading to the scene of a double shooting when they struck a woman near a freeway feeder road, police said in a news briefing at the scene.

The woman, who investigators identified only as a Hispanic female in her 40s, stepped off a curb and into the path of the officer’s vehicle, police said. She was pronounced dead at the scene.

Though the officers were responding to a call, their lights and sirens were off because it was not a code 1 emergency, Houston police said.

HPD defines a code 1 emergency as “an incident in progress with a potential threat to life or bodily injury.”

The officer behind the wheel has been with the department for two years and their partner just one year.

“The officers are shaken up,” police said, adding that they have been put on leave — as is policy — while an investigation is carried out.

Two weeks earlier, a man named Caleb Swafford was walking to a friend’s apartment when he was fatally struck by an HPD patrol vehicle along a road on the city’s north side, McClatchy News previously reported.

Police say the officer was driving down the middle lane around 1 a.m. on Jan. 5, when he hit Swafford, then turned around to perform life-saving measures. Those efforts didn’t succeed and the fire department pronounced Swafford dead a short time later.

“This is not a well-lit area, but we’ve got to figure out all of the different facets that went into this crash,” Sean Teare, Harris County assistant district attorney, said at the scene.

Teare said the investigation would take time, and the results would be brought before a grand jury to decide what charges, if any, should be brought.

“Our understanding right now is the officer was responding to a call,” Teare said. “It wasn’t what we call a code one, so he was not utilizing his lights and sirens. And because of that, it doesn’t appear that speed was a factor at this time, but we don’t have a definitive speed yet. We will, but we don’t have one right now.”

An officer heading to a non-emergency call about 2 a.m. on Dec. 30 was “startled” when he felt “a bump,” and the airbags deployed, while driving along a stretch of U.S. Interstate 10 on the city’s northeast side,Assistant Chief Ernest Garcia said.

The officer pulled off onto the shoulder and “saw there was something on the side of his vehicle,” Garcia said. It was a 35-year-old man.

Like the other two victims, he died at the scene.

Investigators said the man “was in a moving lane of traffic” when he was hit, according to an HPD release.

“We never want to see something like this happen,” Garcia said. “We don’t ever want to see pedestrians cross the freeway, especially at night with limited light.”

The Houston Police Department declined to comment on the incidents, as they are under investigation.

Auto fatalities involving police are often associated with high-speed pursuits, but they can and do happen under a variety of circumstances, Ashley Heiberger, a retired police captain from Pennsylvania who now works as an expert witness, told McClatchy News in a phone interview.

“Sometimes you have people that are walking where they’re not supposed to be, whether it’s because they’re under the influence of alcohol or drugs, or they might have suicidal ideations,” Heiberger said. “It’s certainly a tragedy, but that doesn’t necessarily mean the officer, or any other motorist for that matter, is at fault.”

He added that when police are heading to a scene, particularly if it’s an emergency, they often must multitask — communicating and navigating — while driving at high speed. It’s important that people can see and hear them coming, for everyone’s safety.

“If you do have a situation for an emergency response, or a need for an immediate apprehension … then you want to do everything you can to make sure other people are aware of that response,” Heiberger said. “That means lights and siren.”