Vienna  - A 48-year-old Austrian man allegedly has murdered his wife's parents with a home-made flame-thrower, Austrian news agency APA reported Saturday.

The attack occurred Friday evening.

The suspect's 84-year-old mother-in-law burned to death in her bed after she was torched with a modified propane-gas bottle. As she had lost both legs due to diabetes, she had no way of escaping.

Her 84-year-old husband was found dead outside the house the elderly couple shared with their daughter and son-in-law in Lemberg in Styria province.

Police said an antagonistic relationship between the two couples living under one roof could have led to the murder.

The suspect unsuccessfully tried to kill himself with a knife after the incident and was apprehended by police near the crime scene.

He has been put in an induced coma and has not been interrogated yet. (dpa)