(CNN) -- An Orlando police officer searching for a murder suspect was gunned down Monday, and a sheriff's deputy looking for her killer also died, authorities said.
"To lose two law enforcement officers on this Law Enforcement Officer Appreciation Day, is indeed a tragedy," Orange County Sheriff Jerry Demings said.
Orlando police Master Sgt. Debra Clayton, a 17-year veteran and mother of two, died Monday morning, Orlando Police Chief John Mina said.
"The Orlando Police Department family is heartbroken today," OPD tweeted, along with video of a flag-draped casket. "One of our own was taken in the line of duty. There are no words."
The chief said Clayton was trying to contact a murder suspect at a Walmart at 7:17 a.m. Two minutes later, police received a call of an officer shot.
Witness James Herman told CNN affiliate WFTV the gunman was wearing a security uniform.
"He walked by me, had a security vest and everything," Herman said.
"I was walking down the sidewalk, right past the officer, and I heard her tell him to stop, or whatever, and he shot her. He shot her down."
Herman said the man continued to shoot behind him as he was running from the scene.
Police identified the suspect as Markeith Loyd. Mina said he is also wanted for the killing of a pregnant woman.
Sheriff's deputy killed
Authorities across Orange County scrambled to find Loyd. During the manhunt, a sheriff's deputy was killed in a crash, Demings said.
"Not only did we lose an Orlando police officer today, we lost an Orange County deputy sheriff as well who was traveling on his motorcycle," the sheriff said.
"A motorist turned in front of him. Based on eyewitness testimony, he had a green light, he was not traveling at any (high) rate of speed."
The deputy's name has not been released pending notification of relatives.
A dangerous pursuit
Demings said several law enforcement officers have been injured searching for Loyd. Authorities warn that the murder suspect is armed and dangerous.
At one point during the manhunt, an Orange County sheriff's captain saw a vehicle that appeared to be the suspect's and made a U-turn, Demings said.
The suspect fired at the captain. The captain was not seriously injured, but authorities are now pursuing an attempted murder charge against the suspect.
At least 17 nearby schools are on lockdown as the suspect remains at large, officials said.
While the search continues, Mina said his department is mourning the death of a "hero."
"I've known Debra for 17 years. She was extremely committed to our youth and the community. She did so many different projects in the community. She organized several marches against violence by herself," the police chief said.
"Debra Clayton is a hero, and she gave her life protecting the community that she loved."