Nationwide manhunt for cop killer

FBI wanted poster: 'The unknown suspect is described as approximately 5'8' to 6'0' tall with a slender build.'

(CNN) -- A nationwide manhunt is on for a man who fatally shot one police officer and critically wounded a second in a shootout in Tupelo, Mississippi, on Monday.

'Do not confront this person, notify law enforcement,' urged FBI Special Agent Daniel McMullen, who added that the suspect should be considered armed and dangerous.

The incident began two states away from Mississippi, in Georgia, two days before Christmas, when the man attempted -- but failed -- to rob an Atlanta bank, the FBI said.

A few hours later and 300 miles west, in Tupelo, the same man tried to rob a bank teller but failed, then turned his attention to a customer at a bank ATM, robbing him, the FBI said.

That led to a shootout with police, during which the man fatally shot Tupelo Police Officer Gale Stauffer and wounded another officer, the FBI said Friday.

Representatives of dozens of police agencies attended the funeral for Stauffer on Friday, Tupelo Police Chief Bart Aguirre said Saturday in a telephone interview. More than 300 police vehicles participated in a procession in Stauffer's honor.

'Almost the entire city of Tupelo lined the streets for the procession,' iReporter Lee Anne Grace said Saturday. 'I lost count after 205 police cars, 16 motorcycles.'

Grace, a music teacher at an elementary school, said she realized she knew Stauffer only after seeing his picture in a news story. 'Whenever our crossing guard is out, the Tupelo police sent someone to help out,' she said. 'He was usually the one.'

The eight-year veteran leaves a widow and children, ages 2 and 6.

'To my knowledge, we haven't ever had a fatality,' Aguirre said about his force, which includes 109 officers and two dozen civilian personnel.

The wounded officer, Joseph Maher, 27, has been released from the intensive care unit at North Mississippi Medical Center in Tupelo and moved into a private room, Aguirre said. 'He was able to get up and do some walking yesterday, with assistance.'

The FBI, local banks and businesses are offering a combined reward of $200,000 for information leading to the identification and arrest of the man responsible.

The FBI says the suspect is between 5 feet, 8 inches and 6 feet tall, with a slender build. He was wearing a ski mask, a patterned jacket, khaki pants, black gloves and tennis shoes. Authorities say he may have fled in a gray sedan, possibly a late-model Chrysler 200.

Anyone with information is asked to call 1-800-CALL-FBI.

CNN's Jareen Imam and Holly Yan contributed to this report.