Houston Fire Department officials have confirmed that a woman charged in connection with a fatal fire last week at a Houston day care has fled the country and is now in Nigeria.

HFD spokeswoman Alicia Whitehead said this afternoon they have requested the assistance of the U.S. Marshals Service to locate Jessica Rene Tata, 22, and return her to the U.S.

A law enforcement official who did not want to be identified said Tata left the U.S. for Nigeria on a Delta flight from Atlanta on Saturday night.

Alfredo Perez, a spokesman for the U.S. Marshals Service in Houston, said Tata's case was turned over to the agency around 3 p.m. today by Houston Fire Department investigators.

He said investigators were working to confirm the information provided by HFD investigators. He would not confirm reports that Tata flew from Atlanta to Nigeria on Saturday night.

"We're looking for her," Perez said. "We're actively working this case as a fugitive investigation."

Tata is charged with reckless injury to a child involving serious bodily injury, according to the Harris County District Attorney's Office. The charge could be upgraded and more charges could be filed, officials said.

Bond has been set at $500,000.

Tata operated a home-based day care where seven children were under her supervision when a fire broke out Thursday afternoon.

Charging documents released today quote an arson investigator, T. Wood, who saw an electric stove with a pot containing oil on the burner. "(It) is believed that the burner was left on and was the heat source of the fire," the documents state.

The documents also allege that two witnesses saw Tata, owner of Jackie's Child Care, drive up to the residence in the 2800 block of Crest Park and "within seconds" they heard her screaming and saw smoke coming from inside the building.

The witnesses say Tata was the only adult or employee of the day care either inside the building or running out of the building at the time.

A law enforcement source said Tata had left the children and had gone to a store when the blaze began.

When she returned with a bag of groceries and opened the door, smoke poured out of the house and she began screaming for help, a witness said.

Tata's brother, Ron Tata, 26, has denied those allegations, saying that she was at the house when the fire started and passed out.

Tata was not in custody of law enforcement Sunday night, said Houston Fire Department Chief Investigator Leo Gonzalez, who is heading the arson investigation into the fire. Gonzalez declined to give further details.

Asked if there would be other charges related to the case, said Donna Hawkins, spokeswoman for the Harris County District Attorney's office, said "the case remains under investigation."

The fire at the day care brought emergency responders into a frantic rush to rescue the seven toddlers, ranging in age from 16 months to 3 years, who were in Tata's care.

Four of the children died. Two children are being treated at Shriners Hospital for Children-Galveston and are in critical but stable condition, said Jo Ann Zuniga, spokeswoman for the hospital.

Tracy Dickerson Storms, whose two grandchildren were under Tata's supervision Thursday, was frustrated early Sunday that no charges had yet been filed against her.

Storms' grandson, 3-year-old Shomari Leon Dickerson, of Houston, died after the fire. Her granddaughter, 2-year-old Maykala Dickerson, is still hospitalized.

"Children are dead," said Storms, who spent Sunday afternoon making plans to bury her grandson.

The other children who died after the fire were Elizabeth Kajoh, 19 months, of Cypress; Kendyll Stradford, 20 months, of Katy; and Elias Castillo, 16 months, of Houston.