Hyderabad, Nov 4 (IANS): Daughter-in-law and three grand children of former Congress MP and party candidate for Warangal Lok Sabha by-election, Siricilla Rajaiah, were burnt alive in a fire at his house in Warangal early Wednesday, police said. The daughter-in-law's family doubt if it was a fire accident.

Sarika and her three children Abhinav, 7, Ayan, 3, and Sriyan, 3, were charred to death in the fire in her bedroom on the first floor of the house.

Fire officials reached the scene and extinguished the fire around 6.30 a.m. Mystery shrouds the cause of the fire as senior police officials began probe from all angles.

Police were questioning Rajaiah's son Anil as to what happened last night and if he or others were present in the house. He was also being questioned if he had any problems with his wife.

Sarika's family members in Nizamabad district said they doubt if it was a fire accident. They also ruled out suicide angle, saying Sarika was not a coward.

The Congress had last week named Rajaiah as its candidate for by-election to Warangal (SC) parliamentary constituency scheduled to be held on November 21.

He was elected from the same constituency in 2009 but was defeated last year.