But even as emergency workers followed his orders, they began to suspect something was not quite right about Clark, who claimed to be with U.S. Army Special Forces.
Maybe it was his paunchy stomach, or how he hot-rodded an all-terrain vehicle, kicking up rocks on the riverfront near a boat ramp used to launch rescue missions.
Indeed, authorities Friday continued searching for Billy Clark, an ex-convict from Tallapoosa, Mo. They say he impersonated an army officer to take command of the launch site for nearly two days after 14 people were killed when an Interstate 40 bridge fell in eastern Oklahoma.
Clark is just the latest in a string of alleged impostors who have bluffed their way into restricted areas after national disasters.
Jerome Brandl, who posed as a volunteer firefighter to gain access to the collapsed World Trade Center, was sentenced in March to one to three years in prison.
David Williams of Bay Shore, N.Y., entered the TWA Flight 800 crash site claiming to be an Army Reserve colonel. He was sentenced separately in 1996 to six months in jail for impersonating a doctor.
Catherine Felicitas, who pretended to be a doctor to meet relatives of victims of TWA Flight 800, was also removed from restricted areas after the crash of Swissair Flight 111 in New York in 1998.
Relatives and investigators say Clark, 36, has a history of assuming false identities to gain free meals, free rooms or merchandise.
"It's just a big ego trip," said Lt. Brent Grill, lead police investigator in Van Buren, Ark, where Clark is accused of renting rooms and not paying. "It's a fantasy of his, which becomes a reality when he gets to play the part."
Clark arrived in Webbers Falls just two hours after the May 26 bridge collapse and told Mayor Jewell Horne that he was in charge. He even gave media interviews.
What made him more convincing was that he already knew about one of the victims - Army Capt. Andrew Clements - before any bodies had been pulled from the river, Horne said.
He asked Horne for Clements' briefcase and laptop computer, which had been found in the water, Horne said. He searched them.
"He knew way too much way too early," nurse Melanie James, who had volunteered to help at the riverfront, told the Muskogee Phoenix. "He had the military thing down to a T. He was clean-shaven. He fit the part. His boots were even shined."
Authorities are not sure how Clark knew about Clements, his briefcase or his laptop.
Crawford County, Ark., authorities issued an arrest warrant for Clark Thursday on one charge of felony theft of services, alleging he didn't pay for eight rooms he rented at a Super 8 motel on May 28.
Clark told the motel clerk the rooms were for bridge collapse volunteers and put "Do Not Disturb" signs on seven of the rooms, which were never occupied, Grill said.
He said Clark approached Van Buren police officers who were at the motel on an unrelated call and told them he was a captain with U.S. Special Forces on leave from Pakistan.
The FBI is also investigating the impostor, but won't confirm they're searching for Clark. But Oklahoma Highway Patrol Capt. John Harris said the FBI told him that Clark is their suspect, too.
Grill said police in Searcy, Ark, have seen Clark's car, a powder blue 1985 Ford Mustang with New Mexico license plates. The car's registration gives a Las Cruces, N.M., residence, Grill said.
Clark left the car at a dealership and drove off in a truck he was test-driving, Grill said.
Clark was released from the Central Missouri Correctional Center in Jefferson City on December 11, after serving three years for felony stealing, said Tim Kniest, spokesman for the Missouri Department of Corrections.
He was paroled in Sept. 1999 but absconded two months later before returning to prison in January 2001 to complete his sentence, Kniest said.
Clark was also placed on two years probation in 1999 for passing bad checks in Butler County, just north of his bootheel hometown of Tallapoosa, Kniest said.