Five months after an explosion leveled three rowhomes and killed two people in Baltimore, Fire Chief Niles R. Ford has provided a cause. The explosion was caused by a large natural gas buildup, Ford said at a Tuesday morning news conference.The Fire Department on Wednesday released its reportTwo people were killed Lonnie Herriott, 61, and Joseph Graham, 20 and seven people were injured after three rowhomes exploded on Labyrinth Road in northwest Baltimore in August.“Although five months have gone by, we continue to pray for recovery in this community,” Mayor Brandon Scott said. Ford said the explosion resulted from a buildup of natural gas and that on Aug. 9, the day before the explosion, unpermitted HVAC work was being done in the basement of 4232 Labyrinth Road. A buildup of natural gas formed, which was found to be spiked on four gas meters between 1:30 a.m. to 2 a.m. on Aug. 10. The readings revealed a spike in natural gas levels the morning of the explosion, Ford