Two convicted murderers who broke out of jail were holding a hostage in an armed standoff with lawmen early Thursday at a convenience store in southern Oklahoma after two of their fellow escapees were captured, authorities said.

Curtis Allen Gambill and Joshua Bagwell were holed up in the store at Total gas station near Ardmore on U.S. 70 and were holding a 70-year-old man hostage, said Kym Koch, a spokeswoman with the Oklahoma State Bureau of Investigation.

"We do have negotiations with them and it is going well, but they have not surrendered at this time," FBI spokesman Gary Johnson said.

The hostage has been identified as 70-year-old George West. It was not immediately known if West is the store's owner.

Authorities arrested Chrystal Gale Soto and Charles Jordan outside the store at 9:50 p.m. Wednesday while Jordan was using a pay phone, Koch said. Soto and Jordan fled with Gambill and Bagwell from the Montague County Jail in northern Texas on Jan. 28.

A Carter County sheriff's deputy and an FBI agent went to the gas station after authorities received a tip that the escapees might be there, Johnson said.

The FBI agent recognized Jordan and arrested him. Soto came out of the store and gave up. Gambill and Bagwell refused to come out of the store.

Gambill and Bagwell were believed to be armed with "multiple weapons," Johnson said.

The four escaped jail by overpowering a female guard. They escaped in the guard's sport utility vehicle. In recent days, they have been linked to two burglaries and the theft of a flatbed truck in southern Oklahoma. A .22-caliber rifle was taken in one of the burglaries.

The truck was found in Lake Murray State Park on Saturday, about a mile from where the hostage standoff was taking place. The men have apparently been hiding in the park the last several days, FBI agent Sam Macaluso said.

Gambill, 23, of Terral, and Bagwell, 24, of Waurika, were convicted of the 1996 shotgun killing of Heather Rose Rich, a 16-year-old cheerleader from Waurika. Each had been sentenced to life in prison and had recently been returned to Montague for further proceedings.

Gambill, Bagwell and the victim's former boyfriend said they feared Rich would accuse them of rape after a night of drinking and sex.

They took Rich, who had passed out, to a remote creek bridge in Montague County and shot her repeatedly in the head and back. Her body was found a week later.

Jordan, 30, and Soto, 22, of Bowie, Texas, were jailed on charges stemming from the deaths of an elderly couple in the county.