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DALLAS (CBSDFW.COM) – After the deadly ambush on police officers in downtown Dallas this past summer, many North Texas police departments started to make changes to their procedures in order to better protect their officers, taking measures to prevent such tragedy from happening again.

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But now, after a police officer was shot and killed just outside of the San Antonio Police Department’s headquarters on Sunday morning, cities are taking their preventative measures even further.

The Fort Worth Police Department altered its policy on Monday, mandating that no officer respond to a call alone. They must now have two police vehicles at every call — even for traffic stops.

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Likewise, police officers in Arlington must have backup on all calls. The department took that step back in July. Dallas officers are encouraged to work in pairs, and so are officers in Garland, but it is seen as optional. Police in Plano have stated that some policy changes are coming, but they will not be made public.

With each act of violence against police officers, the need for safety becomes more urgent. “It’s just safer, more productive also knowing there is an officer there watching your back, another set of eyes when lead officer is engaged,” added Sgt. Mike Mata with the Dallas Police Association. “In the world we’re in right now, it’s better to be safe than sorry.”

In addition to the fatal San Antonio incident, there were three other situations where officers were shot on Sunday — one near Kansas City, one in St. Louis and another along coastal Florida.

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“I have to think about it but, at the same time, I can’t let it overshadow what I’m called here to do,” Sr. Cpl. Christine Smith of the Dallas Police Department stated. “I’m supposed to do my job. It’s in the back of my mind, but you put your safety first and you trust your training and I trust the Lord — simple as that.”