Police said the attacker and his victim know each other, but they did not disclose their exact relationship.
The attack left the victim with cuts to her upper body, according to police. Medics took her to a local hospital where she was treated.
The woman posted about the stranger breaking into her home and pinning her to the ground. Police believe it was an isolated incident.
Police said the man and woman had been in a fight when the man sprayed an unknown fuel on the victim and ignited it.
The woman was holding the 7-month-old boy when a 58-year-old man pepper-sprayed them both, police said.
Police said the violent altercation started with an argument outside a home in North Long Beach.
The man had been arguing with the group near a convenience store at the corner of Pacific Coast Highway and Martin Luther King Jr Avenue.
The victim was uncooperative with police.
The victim had been struck on the head by a “blunt object” and any suspects were gone before officers arrived.
Police are investigating two attacks in the same area last night on Anaheim Street near Pacific Avenue.