Ex-Girlfriend Allegedly Killed Colorado Mail Carrier in Broad Daylight While He Was on His Route

A postal worker was gunned down Wednesday afternoon while delivering mail in a Colorado neighborhood, and authorities believe the shooter was his ex-girlfriend.

Police in Longmont have charged 26-year-old Devan Schreiner with the first-degree murder of Jason Schaefer, 33.

Schaefer was fatally shot at approximately 12:33 p.m., according to a statement from the Longmont Police Department.

He was working his route Wednesday when he was killed in "front of neighborhood mailboxes and died at the scene," reads the statement.

Eyewitnesses reported seeing a man in a hooded sweatshirt fleeing the scene. But detectives allege that individual was Schreiner, who is being held without bond.

Police have yet to comment on a motive for the murder, but said Schreiner and Schaefer used to date.

"The Longmont Department of Public Safety wants to assure the community that this was not a random act of violence," the statement explains. "This crime appears to be an isolated incident and an act of domestic violence."

Schaefer, the statement says, was shot several times.

Want to keep up with the latest crime coverage? Sign up for PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases.

KCNC-TV reports that the United States Postal Service of Colorado on Thursday had a procession in Schaefer's honor, with 47 postal trucks driving one-by-one on the same route Schaefer drove Wednesday morning.

Police ask that any witnesses or residents who may have surveillance footage of the shooting contact them at 303-651-8501.

October is Domestic Violence Awareness Month. If you are experiencing domestic violence, call the National Domestic Violence Hotline at 1-800-799-7233, or go to thehotline.org. All calls are toll-free and confidential. The hotline is available 24/7 in more than 170 languages.