A desperate search for two children missing in a rural part of Canada’s Nova Scotia province has stretched into its fourth day, with dozens of rescuers combing the dense woods in search of the siblings.

Six-year-old Lily Sullivan and her brother Jack, 4, were last seen Friday morning at their home in Pictou County, about 70 miles from the province’s capital city of Halifax, according to the Royal Canadian Mounted Police. Police said on Saturday they believe the pair wandered away from their home.

In the days since, more than one hundred searchers as well as helicopters, drones and dogs have been scouring the heavily wooded area near their home for any clues about the siblings’ whereabouts.

“It has been a few days, but that has not dampened the hopes of the (search) teams and the police who are here trying to get these kids home,” Corporal Carlie McCann, a spokesperson for the Royal Canadian Mounted Police (RCMP) told reporters Monday, according to CNN affiliate CBC News.

The search continued overnight Monday despite challenging rainy conditions. Police said searchers spotted a footprint on Saturday and have expanded their search effort in that area, CBC reported.

The children’s mother, Malehya Brooks-Murray, told CNN affiliate CTV News that she woke up Friday morning and heard the kids playing in the next room before drifting back to sleep. When she woke up and noticed they were gone, she immediately called 911.

Brooks-Murray told CTV Jack and Lily are not the type of kids to go outside alone.

“We always make sure that we’re out there with them, watching them, and they happen to just get out that sliding door, and we can’t hear it when it opens, and they were outside playing, but we weren’t aware of it at the time, and the next thing we knew it was quiet,” Brooks-Murray told CTV.

The children are members of the Sipekne’katik First Nation, according to chief Michelle Glasgow.

“Please help bring Lily and Jack back home,” Glasgow said on social media.

Daniel Martell, the children’s stepfather, told CBC Lily and Jack are “awesome kids.”

“Jack just absolutely loves bugs, dinosaurs,” Martell said. “Lily loves girly things but she also loves doing everything with Jack.”

“They’re like best friends, not just brother and sister,” he added.

Martell said he is pushing for police to monitor the borders and the airports to search for the children. The RCMP are not currently treating the case as a possible kidnapping, according to the CBC.

The RCMP said search and rescue volunteers and officers have “meticulously searched” the area around Jack and Lily’s home and asked the public to avoid the search area in a post to social media Monday.

“Searchers are diligently keeping track of which specific sections of the ground have been covered and are applying their specialized skills to allow the searchers on scene to stay safe,” the RCMP said.

Nova Scotia Premier Tim Houston said people “across Nova Scotia are praying for a positive outcome” for Jack and Lily in a post to social media Saturday.