A 2-year-old girl and her 6-year-old brother died after an explosion and fire in their Montgomery County home yesterday.

Their mother suffered burns trying to save them. The fire in Collegeville also injured a third sibling, a boy, age 3.

Investigators were still trying to determine the cause of the fire last night.

Collegeville police said witnesses called at 11:46 a.m. with reports of an explosion and smoke coming from the two-story house at 423 Park Ave.

Kristy L. Beto, 22, had escaped out a back door and was reportedly trying to reach her children but had already been burned.

A neighbor rescued Dylan Beto, 3, but could not save Anthony Claxton, 6. Firefighters and police pulled Mikayla Beto, 2, from the house 14 minutes after the call came in, but she later died at Phoenixville Hospital.

Dylan Beto was taken to St. Christopher's Hospital in Philadelphia. His mother was taken to Temple University Medical Center. Their conditions were unavailable last night.

Six fire companies responded. The Collegeville police and fire marshal, Montgomery County Detectives, and state police were all investigating.

Contact staff writer Jeff Shields at 215-854-4565 or jshields@phillynews.com.