In New York, one group says it's taking no chances.
After multiple women have been killed while out jogging in recent days, some runners are changing they're exercising habits.
Read: Family of Murdered New York Jogger Wants to Raise $100,000 Reward to Find Her Killer
Some say they're steering clear of jogging by themselves on isolated trails and instead, they're signing up for running groups to make sure there are always other joggers around.
In New York, members of the jogging group She Runs This Town are taking no chances.
"All of us are on alert and wherever possible we prefer to run with somebody," one runner told Inside Edition.
Runners are also being advised to keep the music down or ditch their headphones entirely.
In Los Angeles, a group of women joggers has similar concerns.
"You have to take precaution, whether it is taking a friend with you or going earlier in the day," one L.A. runner said.
Google employee Vanessa Marcotte, who lived in New York City, was slain as she ran near her mother's home in Massachusetts
Six days earlier, Karina Vetrano was found dead after she went for a jog on a remote path in Queens, New York.
Read: Murder of Jogger, 27, in Massachusetts Shares Eerie Similarities With New York Killing
Attention is also focused on a third female jogger who was found slain on July 30. Alexandra Brueger, 31, was shot in the back as she took her daily 10-mile run near her home outside Flint, Michigan.
Michigan State Police are asking if anyone who saw a white or light-colored four-door vehicle to call 855-MICH-TIP. The vehicle was seen driving around the area when the woman was shot.
Watch: After the Grisly Death of Jogger, How You Can Stay Safe During a Run
