Police are still searching for the gunman at the centre of a shooting and manhunt in the Horowhenua town of Foxton. 

The victim of the shooting arrived at Palmerston North Hospital in a critical condition following the incident and a MidCentral District Health Board spokeswoman could not confirm the status of the victim at 4.30pm on Monday.

Police said the shooting took place at a Main St property on Monday morning, with one person suffering serious injuries, believed to be to their leg.

Crime scene cordons went up just before midday, forcing schools and the public library in the Horowhenua town into lockdown.

Schools in the area began lifting their lockdowns about 1pm as the hunt for the gunman continued.

The gunman remained on the loose and was thought to still be in the Foxton area, police said about 2pm. They added shortly afterwards that cordons were coming down "gradually".

It's understood the offender on the run was wearing a Nomads gang vest. One woman told Stuff the shooting had occurred at a flat on Main St. 

A spokeswoman at Manawatū College said it went into lockdown about 11.40am.

The school was out of lockdown after 1pm, and others were told they could also do the same.

Shortly before 12.30pm, armed police had cordoned off an alleyway on Main St, next to Hammer Hardware.

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The alleyway led to a space at the end of Foxton Service Lane, off Wharf Rd. Police herded out several bystanders to tape off the whole area behind the shops.

A couple of police officers were standing on a second-storey fire escape, where their efforts seemed to be concentrated.

A witness told Stuff police briefly detained a man next door to a car yard, Lee Mason Motors, but let him go.

Children hid under desks for an hour at Foxton Primary School while police searched for an alleged gunman in Foxton.

School principal Tiwana Hibbs, on his first day in the job, said the school was called by police about 11.40am and told to go into lockdown.

"We were unaware of what happened and no details were passed [on] by police."

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Children were told to get under their desks or hide in backrooms and keep quiet.

The school had practised the procedure, but the real thing was confronting, Hibbs said.

"The emotions were running high. We had a lot of kids who were very scared.

"The staff did an amazing job of keeping them quiet and out of sight."

Worried parents flocked to the school and some had taken their children home after the lockdown was lifted about 12.40pm.

The school would be monitoring the children. "They were really rattled. We'll be making sure they're fine."

Te Awahou Nieuwe Stroom marketing manager Arjan van der Boon said the library and cultural centre were also placed into lockdown, which finished after 1pm.

​Some people were in the attached cafe enjoying food, while small snacks were being given to everyone else.

"People are keen to leave, but we can't let them out."

A group of nursing students, who had been using one of the rooms in the building, were helping distribute snacks.

"It's good training for them, I suppose," van der Boon said.

He had not seen much apart from two police cars going past the centre.

Ousted Horowhenua mayor Michael Feyen said he saw police apprehend a man on Hall St close to 2pm. Police said they had not arrested anyone in connection with the shooting.

A police photographer was working behind the cordoned-off alleyway off Main St just after 1pm. The police presence in the area behind the alleyway appeared to have relaxed by then.

Police at the scene would not comment to reporters or the public.

A Foxton resident of 30 years, who didn't want to be named, said she knew one of the parties involved in the shooting, which she said was appalling.

Armed police were at 1pm stationed at the corner of Main St and State Highway 1, the southern end of the town.

Two decades ago the Nomads – a Black Power breakaway – were a fearsome street gang.

The building on Main St where police activity was centered.

Police launched a massive crackdown in 1994. Mark Lammas, who was the Palmerston North police district commander at the time, said Nomads "to a large extent, had the community cowered down".