A covered patio seems to be the starting point of the Nov. 16 five-alarm fire at Barclay Friends continuing care retirement community in which four residents died, according to Bureau of Alcohol, Tobacco and Firearms investigators. Agents remain unsure, however, of what caused the West Chester, PA, fire or how it spread, according to local media reports.

ATF spokeswoman Charlene Hennessy said the fire at the Kendal Corp. CCRC appears to be accidental but that the investigation is ongoing, CBS Philly reported on Friday. Agents also are conducting tests to see whether the sprinkler system was operating properly, Hennessy said.

The Chester County Coroner’s Office previously identified the four deceased residents as Mildred Gadde, 93; Theresa Malloy, 85; and Delores Parker, 89, and her husband, Thomas Parker, 92. Twenty-seven additional residents were injured in the fire, according to the community.

In a message posted Thursday on its website, Barclay Friends said it continues to work with investigators to determine the cause of the fire and to work with residents, family and staff members to meet their needs. The community said it plans to hold meetings with families this week.

The CCRC said it plans to demolish the building where the fire broke out and that it hopes to reopen its skilled nursing building as soon as possible, although dates have not been set.

In the meantime, Barclay Friends staff members and volunteers are preparing “Secret Santa” packages for residents, according to the post. First Presbyterian Church of West Chester is helping to coordinate the effort; people can sign up to volunteer or donate here, if interested.