Three months' worth of rain over the course of one day has flooded the Canadian province of Nova Scotia since Friday night, inundating streets, forcing evacuations and leaving at least four people missing -- including two children.

A provincewide state of emergency has been declared, including for the Halifax regional municipality as well as nearby East Hants, West Hants, Lunenburg and Queens.

"We have had biblical proportions of rain over the night and into the day," Halifax Mayor Mike Savage said Saturday.

The two missing children were passengers in a vehicle that became submerged under water in West Hants, Premier Tim Houston said in a press conference Saturday. Three others who were in the car with them were able to escape, he said.

In a separate incident, a young person and a man were also reported missing in the West Hants area after their vehicle was submerged, while two other passengers traveling in the same vehicle were rescued, Houston said.

Officials have not released the names or ages of the four as the search for them continues.

"I cannot stop thinking about these families and these four individuals," Houston said. "I want them to know that everything that can be done is being done. I know the entire province joins me in praying for their safe return."

Houston warned that conditions in the area are still dangerous and asked community members to pause on joining the search for the missing people.

Northern and eastern Nova Scotia are expected to see more rain Saturday night, while the forecast predicts rain in the central, western and southern areas will ease, officials said.

An estimated 250 millimeters of rain battered the province in one day, Houston said.

"We got three months' worth of rain in less than 24 hours," he said. "It came fast and it came furious."

Much of central Nova Scotia has seen severe flooding that deluged roads, forced water rescues and left "significant" property damage Saturday, Houston said. The storms have also compromised bridges and damaged highways.

The state of emergency declaration is meant to limit travel in heavily impacted areas, allow for the deployment of assets and facilitate the restoration of affected infrastructure, officials said.

"We have a scary situation here in the province. We had significant rainfall overnight causing extensive flooding damage," said Houston. "The state of emergency allows us to respond quickly when there are calls for more resources."

About 750 people were ordered to flee the Halifax area overnight, while more than 400 homes were evacuated in Lunenburg, authorities said Saturday.

In East Hants, a bridge collapse stranded residents, and there were "about several hundred people there that are sheltering on site and they're self-sufficient," said Kelly Ash, East Hants emergency management coordinator.

As local and federal agencies continue to use resources to repair damaged bridges, highways and properties, officials say it will take days for any improvements before the water level settles down.

"Once again, our community is facing the awful force and unpredictability, nature and a changing climate," Mayor Savage said.

"This has been an extraordinary event and I know that it follows on the heels of wildfires of not very long ago and even Hurricane Fiona of last fall." the mayor added.

Some communities in the Halifax area are still recovering from a large wildlife that started in late May, which led to evacuation orders for about 16,400 residents and destroyed 151 homes, CNN Canadian partner CBC reported.

Prime Minister Justin Trudeau offered support to Nova Scotia residents in a post on Twitter Saturday afternoon, saying that with air and marine assistance "we're providing resources to help with evacuations -- and we stand ready to provide any additional federal resources needed. Please stay safe, everyone."

Trudeau also spoke with Houston Saturday and emphasized federal and local collaboration on search and rescue efforts, Trudeau's office said in a news release.

"The Prime Minister reiterated the Government of Canada's commitment to supporting Nova Scotians in the days and weeks ahead to respond to the flooding," the release said. "He also acknowledged the strength of Nova Scotians, who are coming together in hard times and showing up for each other."