The bottle filled with petrol and with a lit wick was thrown at the house in Ramkhamhaeng Soi 12 in Ramkhamhaeng area of Bangkok about 3.30am Thursday. The house belongs to Ms Chitpas’ father Jutinan Bhirombhakdi.
The attack occurred about an hour after Ms Chitpas returned to the house.
The firebomb damaged a van parked inside the grounds.
Security guards at the house told police that four men wearing crash helmets and riding motorcycles arrived in front of the house. They tossed the firebomb into the grounds and fled away. The residence has CCTV security cameras, which captured images of the men.
The police suspect the motive was political.