A Molotov cocktail was hurled into the Sha Tin home of two missionaries yesterday, setting furniture alight. The attack came just weeks after the couple were tied up and robbed by four illegal immigrants at their home. Early yesterday morning, a bottle filled with paint thinner was lobbed into the ground-floor living room of their house in Chap Wai Kon Street, Siu Lek Yuen. At the time of the incident, the couple - whose nationality has not been revealed - was in the United States. Their daughter, a teacher, returned from the mainland yesterday. The glass door of the ground-floor balcony was broken open before the home-made bomb was thrown into the house, said Siu Lek Yuen divisional commander, Superintendent Tommy Chau Siu-keung. 'The lit bottle hit a sofa and bounced to the floor but was not broken. Some thinner leaked out from the bottle and set the sofa alight, causing dense smoke,' he said. A neighbour woken by the noise called police. Firefighters put out the blaze at 5am. Mr Chau said they were investigating whether the attack was linked to the earlier robbery. The couple has lived in Hong Kong for more than 10 years.