Concern mounts as an extremely aggressive blaze on Martin Mountain rips through the area.

A remnant of the Aug. 20 thunderstorm — in which lightning struck 70 times in the Kamloops area and more than 300 times in the Shuswap — the wildfire rekindled last Thursday night and, by noon on Friday, was 400 hectares in size and growing.

More than 100 people and dozens of animals were forced out of their homes and another 150 residents remain on evacuation alert.

Elise Riedlinger, fire information officer for the Kamloops Fire Centre, said days of high temperatures, low humidity and strong winds are being blamed for the resurgence of the fire.

"The Martin Mountain fire took off north and has extremely active fire behaviour," Riedlinger said, noting the 400-hectare spread happened mostly within last 24 hours.

"We have air tankers on site and they are lying retardant lines on the north and northwest flanks of the fire."

The centre is on high alert as the temperatures are expected to stay in the low- to mid-30s through the weekend and thunderstorms with dry lightning are expected on Friday and Saturday nights.

And unusually low humidity levels also add to the already unstable conditions.

"There will be extremely low relative humidity, dropping below 10 per cent — it's something we rarely see," Riedlinger said.

"It's just really dry conditions right now and it's prime conditions for extremely active fire activity."

In the meantime, there are helicopter crews in the air with the waterbombers and six local fire departments and the B.C. Forest Service fighting from the ground and trying to protect the homes in the path of the blaze.

At 4:30 a.m. on Friday morning, the Thompson-Nicola Regional District evacuated residents from the 5100- to 5600-blocks of Martin Prairie Road, all of Cober and Cory Roads and Silver Birch Lane.

"We were told this morning the fire has been ranked at six out of seven in terms of the fire's erratic behaviour and it's very close to some homes at this moment," said Liz Cornwell, information officer for the TNRD's emergency operations centre, noting there are personnel on site, closely watching the fire's movements in order to evacuate immediately if necessary.

"It's just one of these things where we're doing the best we can to ensure those people are safe."

An Emergency Social Services (ESS) reception centre is set up at the McArthur Island Complex for evacuees.

Those evacuated, but not using these services are asked to register with ESS to make sure all evacuees are safe.

The Kamloops SPCA has made arrangements to have large livestock housed at the KXA grounds and the Ministry of Forest and Range is making arrangements to move any animals still up in the area.

For more information or to register with ESS, call 250-828-3722.