Dogs will search today for traces of accelerant at the site of a massive mansion fire, where six are presumed dead.

Technology tycoon Donald Pyle, his wife and his four grandchildren are missing following a fire at his $9 million home in Annapolis, Md.

Authorities are now investigating whether accelerant was used to spread the fire.

Read more from MyFoxDC.com:

Investigators brought in a heavy crane and other equipment Tuesday to help in the search for six family members who are still missing after a massive fire at an Annapolis mansion on Monday. Authorities say tons of steel will have to be moved before a search can be conducted in the basement of the mansion on Childs Point Road, which burned to the ground. 

Late Tuesday morning, workers moved branches and wires so the heavy-duty crane could make its way to the mansion. The crane will be used to hoist large pieces of steel out of the basement of the house, which is equal to the size of five standard homes.

Anne Arundel County Fire Captain Robert Howarth says the house is 16,000 square feet, and everything it was made of has fallen into the basement, including steel beams that weigh several tons. Late Tuesday morning, a fire was still burning in the basement.

"Over the next day or so, we hope to be able to move some of the debris so we can get the investigators in there and find the unaccounted-for victims," he said.