A man angered after a dispute with his wife confessed to tossing his four young children off a bridge, authorities said Wednesday as they searched murky waters for the bodies. Lam Luong, 37, who is charged with four counts of capital murder, told authorities Tuesday night that he drove to the Dauphin Island bridge and dropped the children from a span that reaches 80 feet in places, said Detective Scott Rivera. Luong came to coastal Alabama from Vietnam in 1984 and worked in the commercial fishing industry as a shrimper, Police Chief John Joyner and a relative said. He had argued with his wife, Ngoc Phan, before taking the children, he said.

Missing and presumed dead were 4-month-old Danny Luong; 1-year-old Lindsey Luong; 2-year-old Hannah Luong; and 3-year-old Ryan Phan. Phan is not the man's biological child, but Luong raised him from infancy, authorities said.

At least three boats were being used in the search, and the Coast Guard was sending another boat and a helicopter, Riva said.

Joyner said he feared the search of the Intracoastal Waterway below the bridge would be hampered by bad weather and choppy waters. The bridge extends from the mainland to Dauphin Island, which lies between the waterway and the Gulf of Mexico.

"It's been a nightmare," said Riva.

The couple lived with Phan's mother at Bayou La Batre, a fishing village with a large Southeast Asian community. Phan's brother-in-law Kam Phengsisomboun, who is from Thailand, said the couple moved back to the area from Hinesville, Ga., only a couple of weeks ago.

They argued Sunday night and again Monday, he said. Luong left the home with two of the children, then later came back for the other two, he said.

The family initially feared the children had been traded to support a drug habit, Phengsisomboun said. Luong had a crack cocaine habit and had spent an insurance settlement from an automobile accident rapidly, he said, and authorities confirmed Luong had a history of drug offenses.

Luong reported the children missing Monday, and told police that a woman who had the children failed to return them, authorities said. Phengsisomboun said he was later told by investigators that a witness had seen someone throw a bundle from the bridge and then saw three children in a nearby car.

Phan, 23, was in seclusion Wednesday morning at her mother's brick home, the front porch cluttered with children's shoes.