SAN ANTONIO -- At least five people were injured in three separate house fires Monday.

The first fire happened around 5 p.m. in the 1100 block of Muncey Street near New Braunfels Avenue and Interstate 35.

Neighbors told KSAT 12 News that they helped a woman and her 6-year-old son escape their 4,000-square-foot home.

The woman was hospitalized for possible smoke inhalation. Her son was not injured, but fire officials said he may have been playing with matches.

The flames were so intense at one point that at least two firefighters were forced to use the ladder to escape.

Around the same time, an explosion in a garage was blamed for a fire in Olmos Park.

Fire officials said it appears a man who lives at a home in the 1500 block of West Hermosa Drive was working on his car in the garage when an explosion occurred.

Neighbors reported the man and his wife stumbled out of the home.

"I asked him, 'Is everything OK? Who is back there?'" a neighbor said. "He said, 'I don't know, I don't know.'"

The man and his wife were taken to a hospital in an undetermined condition. At least two firefighters were treated for smoke inhalation at the scene.

About four hours later, firefighters arrived at a home in the 19700 block of Encino Brook on the city's far north side to find the second floor of the residence fully engulfed in flames.

No one was home at the time, fire officials said.

Damage was estimated at $80,000.