Investigators are still looking into whether or not the attacks on Ohio State University's campus are terror related.
The attack is a reminder that this type of violence can happen anywhere.
"I hope one day we don't have to be fearful, and we can straighten this mess out," said Maricopa County Sheriff Joe Arpaio.
But until then, law enforcement is asking everyone to pay attention to everything that's going on around them.
"We should watch out because you don't just use weapons to hurt people. A vehicle is a dangerous weapon," said Sheriff Arpaio.
In fact, that's the latest request made by ISIS. They want sympathizers to use what they have to hurt as many people as possible.
"We are at war in this country. It proves a point, regardless of whether this is a terror attack, it shows anything can happen on any day with people who will do something and kill people," Sheriff Arpaio said.
The most vulnerable spots are soft targets: areas with a lot of people and minimal security, such as schools, malls and sporting arenas. Other examples include airports, hospitals, movie theaters, hotels, restaurants, nightclubs and public transportation.
The Arizona Counter Terrorism Information Center, known as ACTIC, is constantly monitoring for threats and Valley law enforcement agencies train year-round for worst-case scenarios.
Sheriff Arpaio includes terror and active shooter training for posse members so they are ready for anything as they patrol the malls during the holiday season.
ACTIC has a video that gives you some tips if you are caught in an active shooter situation.
And while law enforcement is prepared to respond, the key is prevention.
So see something, say something, you could be saving lives.