(CNN) -- There is a $25,000 reward for information leading to the arrest and conviction of whoever fatally shot two female postal workers Monday morning in a western Tennessee post office, federal postal authorities said.

The incident in the town of Henning, about 50 miles northeast of Memphis, was reported shortly before 9 a.m. (10 a.m. ET) in a 911 call to the Lauderdale County Sheriff's Department, said District Attorney Mike Dunavant., who would not divulge who made the call.

About five people typically work in the post office at any given time, though Beth Barnett, the U.S. Postal Service's manager of communications, said she did not know how many were on duty at the time of the shooting.

Hours after the shootings, neither she nor Dunavant reported much new information. He would not identify the victims of what he called "disturbing violence," pending notification of their families.

"We're not releasing any other information pending further investigation and notification of family members," Barnett told reporters.

The U.S. Postal Service is the lead investigative agency, backed up by the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives, the Tennessee Bureau of Investigation, the Tennessee Highway Patrol, the Lauderdale County Sheriff's Department, the Tipton County Sheriff's Department and agents from the 25th Judicial District Drug Task Force, said Dunavant.

"Multiple agencies are working on this diligently and following every lead possible," he said.

Forensics investigators with the Tennessee Bureau of Investigation's Memphis crime lab were processing the scene for evidence, said spokeswoman Kristin Helm.

The Memphis Commercial Appeal said the incident happened during an apparent robbery attempt at the post office, though neither Dunavant nor Barnett would confirm that.

CNN affiliate WMC reported that police are searching for two suspects who left the scene in a maroon Chevrolet Malibu, another assertion that neither of the officials would confirm.

But Dunavant did confirm that the suspects are considered armed and dangerous.

Postal Inspector Michael Romano said such incidents are not common. "This is definitely rare," he said in a telephone interview. "This is not something we deal with" on a regular basis.

Emma Rucker, who said she lives about a 10-minute walk from the post office, said she heard about the shooting from her sister, who called to tell her. "That got me," she said, adding that crime is rare in the neighborhood. "It's quiet," she said.