HUDSON — Police Chief Edward Moore said he knew there would be retaliation after a 28-year-old woman was shot in the shoulder Saturday night.

That's why he had three police officers stationed outside a 543 State St. home Sunday night. But their presence was not enough of a deterrence, he said.

Just before 9 p.m., a man approached the house and used the porch as cover as he shot several rounds into the backyard, the chief said. Someone else returned fire.

"They still pulled it off and that's extremely troubling," Moore said. No arrests had been made as of 8 a.m. Tuesday, he said.

As the bullets flew, "a mother laid on top of her 2-year-old girl and got shot through the leg," Moore said. The toddler was shot in the knee and, inside the house, a 3-year-old boy was struck in the leg. All are expected to survive.

Police did not know the boy had been shot until hours later, when the child emerged from hiding inside the State Street home to meet his father, who had arrived to pick him up, Lt. Anthony Moon said. Once in his father's car, the boy complained his knee hurt, Moon said.

"Well, sure it does," the chief said. "There's a bullet in it."

The family rushed the boy to Albany Medical Center Hospital, where the bullet was removed Monday morning, Moore said.

"This is senseless," Moore said. "It's motivated by emotions and is very, very bold."

On Monday morning, as State Police evidence technicians and Hudson detectives scoured the State Street property — which the chief described as "riddled with shell casings and bullet holes" — city officers rushed to investigate reports of someone brandishing a gun. Moore said no arrests were made but it likely was the same group of people involved in both the Saturday and Sunday night shootings.

"This is an escalation of an ongoing battle between two factions," Moore said, hesitating to call them gangs based on their loose associations. He described them as "people who have vendettas, grievances and anger that dates way back."

"We know every person we suspect was involved in this," he said.

He called it unfair that the violence would tarnish the image of the city, a popular spot for fine dining and antiquing.

"It's perpetrated by a handful, maybe six or eight people. It's blatantly unfair," he said.

Moon said, "We've dealt with them quite a bit." Police are trying to understand what is fueling the ongoing feud, whether other illicit activities are involved and how the groups are connected, he said. Some people on both sides are related, Moon said.

The chief said the violence began in early May, when a man was shot on the 500 block of State Street, between North Fifth and North Sixth streets. Weeks later, the same people were involved in a shootout at the Half Moon Bar on South Front Street, Moore said. Cars were damaged by bullets. Police seized a .45 caliber handgun after that incident, he said.

Then, on Saturday, the 28-year-old woman was shot a block away from where Sunday's shooting occurred, the chief said.

The chief said that, while he urges Hudson residents to stay calm, he understands their trepidation.

"It's isolated between very small groups," Moore said. "But it's hard to convince people it's isolated when bullets are whizzing by and kids are getting shot."

Michael Leighton, who lives three doors down from 543 State St., said he heard the gunshots from both shootings.

"I heard the ruckus Saturday: 'Bang, bang, bang, bang, bang,'" he recalled. "We didn't know if it was fireworks or gunshots."

The sound of police sirens was his answer, Leighton said. Soon after, a detective knocked on his door to learn what he had heard.

"Then the surprise came last night, with the bang, bang again," Leighton said Monday.

His wife, Jeanette Wolfberg, said she was in the kitchen when she heard "loud pops" Sunday night and quickly moved to the center of the house for protection. When the shooting stopped, Wolfberg said she came outside to find the street filled with police cars.

Leighton and Wolfberg stood outside Monday morning watching State Police forensic investigators scour their backyard and three others for clues. Bullet holes punctured their wooden fence.

"This is a highly specific event," Leighton said, adding it doesn't change his view of Hudson. The couple has lived in the city for about five years.