JACKSON (AP) — Authorities believe the 5-month-old girl rescued Sunday after allegedly being kidnapped by her biological mother at gunpoint from her northeast Mississippi home was the subject of a custody fight.

Madison Erickson was recovered unharmed at Fort Bragg, N.C., and two arrests have been made. An FBI spokesman said agents and Fort Bragg military police arrested the baby’s biological mother, Jamie Kiefer, and her sister, Rikki Swann, at about 4:40 a.m.

Authorities are still looking for a man and a woman they say participated in the early Saturday abduction.

The sisters were arrested and the baby was recovered at a base housing unit put under surveillance early Sunday, FBI Special Agent Jason Pack said. Authorities believe Kiefer was in the group that broke into the home of Madison’s adopted parents, Jennifer and Matt Erickson, and took the baby. Swann faces kidnapping-related charges for allegedly helping Kiefer afterward.

Madison, a petite brunette who weighs 13 pounds, was examined at Womack Army Medical Center at Fort Bragg and turned over to child welfare workers while the Ericksons traveled from Mississippi to North Carolina to retrieve the girl.

‘‘Apparently (the kidnapping) was related to the adoption of the baby,’’ Pack said. ‘‘Apparently Ms. Kiefer had changed her mind about the adoption.’’

Amanda Bell, who lives in the Fort Bragg apartment where Kiefer and Swann were arrested, said Madison appeared to be healthy but ‘‘was getting traumatized by all the people who were trying to snatch her from her mother.’’

Bell said she is friends with Swann, who was staying with her, but did not know Kiefer and Madison were in her home until agents and military police arrived.

Eighteen hours earlier three masked invaders stormed into the Ericksons’ home north of Mantachie on rural Mississippi 363 North, Itawamba County Sheriff Phil Crane said. They tied up Jennifer Erickson with an electric cord, but left another young child of Erickson’s alone before fleeing with the baby.

Erickson was able to free herself and called authorities.

Crane said the Ericksons have had the baby for most of her short life, but that the adoption was being disputed.

‘‘I think this had been in court not too long ago,’’ Crane said. ‘‘So this was an ongoing situation.’’

The Ericksons were unavailable for comment. Crane, who gave details of the kidnapping and arrest during an afternoon news conference, said he knows little about the adoption.

Authorities issued an Amber Alert to help find the baby Saturday afternoon. It was the second successful use of an alert in a week and just the fourth use of one in Mississippi since the program started in 2002.

They initially thought there was no connection between the family and the kidnappers, but later began looking for Kiefer as their investigation developed.

Swann was ‘‘hysterical’’ when she called Bell at about 11:30 p.m. Saturday to ask if she could visit. Swann had been on vacation in Atlanta and heard about the kidnapping, Bell said. Swann lived at Fort Bragg before returning to Mississippi when her husband deployed to Afghanistan. Bell’s husband is in the same unit and also is deployed.

‘‘She said I was the only person she knew over here (in the eastern U.S.), and I said, ’Fine,’’’ Bell said. ‘‘We’re best friends.’’

Bell has known Swann since October when their husbands introduced them. She doesn’t believe Swann could have participated in the kidnapping.

‘‘I know Rikki and that woman could not do anything like that,’’ Bell said. ‘‘She’s like 5-2 and she’s a puppy.’’

Pack said authorities are still trying to develop leads on the man and second woman allegedly involved in the kidnapping.

Kiefer and Swann will be transferred to the Cumberland County jail Sunday to await extradition to Mississippi. Pack said they could face federal kidnapping and related charges in either Mississippi or North Carolina. He didn’t expect them to make an initial court appearance until Monday or early this week.

Pack said the women are from Belmont, Miss., a town of about 2,000 in Tishomingo County. He did not have Kiefer and Swann’s ages, but said both are in their 20s. Swann has three children who Bell was caring for Sunday while Kiefer and Swann’s parents travel from Mississippi to Fort Bragg. Kiefer also had a second child at the apartment, a 5-year-old boy, who was taken to Womack Army Medical Center for a routine medical examination and turned over to Department of Social Services.

U.S. Army spokesman Col. Bill Buckner said members of the Mississippi FBI contacted Fort Bragg police after midnight Sunday. Agents and military police searched the area and found a white van with Mississippi plates. They set up surveillance around 3 a.m. and watched the van and apartment while obtaining warrants.