HOLDEN, La. (AP) — A man shot his estranged wife, son and 2-year-old grandson to death and seriously wounded his pregnant daughter-in-law at their rural Louisiana home, then killed himself as police tried to pull over his car 20 minutes later, authorities said.

The pregnant woman later gave birth, about three months early, her father said. The shootings appeared to stem from an ongoing dispute between 50-year-old Dennis Carter Sr. and his wife, Donna Carter, who had a restraining order against him, Livingston Parish Sheriff’s Office Chief of Operations Perry Rushing said Sunday.

The father of the pregnant woman, Amber Carter, said the suspect had a history of abusing his estranged wife and recently tried to attack her with a machete.

‘‘This had been going on for quite some time,’’ Paul Williamson said. ‘‘It was one of those domestic violence things that just gets worse and worse.’’

Another 16-month-old boy was in the house during the shootings but was not hurt. The child was related to the Carters but Rushing was not sure how.

Authorities were called around 10:30 p.m. Saturday to the home in Holden, about 30 miles east of Baton Rouge. Donna Carter, 49, and Dennis Carter Jr., 26, were dead inside. Dennis Carter Jr.’s wife, Amber Carter, was badly hurt and their son, Masson Carter, 2, was found dead outside.

Williamson said Carter Jr. had previously fought with his father to protect his mother.

Rushing said it appeared Amber Carter, who was about six months pregnant, and Masson Carter managed to escape from a second-floor window but it was not clear if the gunman shot them inside or followed them outside and shot them there.

Rushing said deputies spotted Dennis Carter Sr. about 20 minutes after the shootings driving on a highway. When they tried to pull him over, he shot and killed himself.

‘‘It’s very unusual to have this many victims,’’ Rushing said. ‘‘This is an anomaly by any stretch of the imagination.’’

All the Carters lived at the house in Holden except Dennis Carter Sr., who used to live there but had recently been residing in nearby Hammond. Williamson said Carter Jr. and wife Amber had been planning to move out of the house where the shootings occurred.

Williamson said the senior Carter was a semi-employed mechanic.

He said his pregnant daughter had bullet wounds to the kidney and liver and spinal damage caused by her leap from a second-story window.

After the shootings, she gave birth to a healthy baby boy named Aubrey, Williamson said. He said she was taken initially to a Baton Rouge hospital and later was transferred to a hospital in New Orleans.

Rushing said that state police ballistics experts were conducting tests on a gun found in the senior Carter’s car.

Williamson said he didn’t expect to ever learn fully how the killing spree transpired.

‘‘We won’t ever know what happened inside that house,’’ he said.