Malappuram district police sources said some steel pieces were found near the blast site and it is suspected that a 'pressure cooker' was used to trigger it.
Kerala Chief Minister Pinarayi Vijayan has said the gang members involved in the crime have been identified and they will be arrested very soon.
Cautioning against the presence of Jihadis, who try to cultivate communalism, religious disharmony, intolerance and contempt across the world, in Kerala also, the Bishop said they were using different means to destroy other religions.
A noted South Indian film actress was harassed for two hours allegedly by a gang of five men, who forced their way into her car before fleeing at a busy area in Kochi.
The Jalandhar bishop of the Roman Catholic church was grilled by the SIT for 7 hours on Wednesday.
The couple-Rajan, 47, and his wife Ambili, 40, natives of Nellimoodu at nearby Neyyattinkara- succumbed to burns at the government medical college hospital in Thiruvananthapuram after they sustained multiple organ failure on Monday.
Police said 34-year-old Rajesh's left hand was chopped off in the attack which took place around 9 pm on Saturday night.
The arrest of two Dalit sisters, daughters of a local Congress leader, for allegedly attacking a Communist Party of India-Marxist activist in Kerala's Thalassery has kicked up a row with the Congress and the Bharatiya Janata Party attacking the Left Democratic Front government over the issue, even as a local court granted them bail on Saturday.
Fearing violent response from the mob present outside the Police Club and court complex, several rings of security were thrown around Islam who was seen wearing a helmet. Before producing him in the court, he was interrogated by top officials of the Special Investigation Team probing the case.
The director general of police said everyone in the force should have to perform their duties irrespective of their religion and politics.
Travancore Devaswom Board, which manages the shrine, said revenue collection on the opening day registered a growth of Rs 1.28 crore compared to last year.
The gold, weighing over 30 kg, was seized from the "diplomatic baggage" that had landed by air cargo at the Thiruvananthapuram international airport recently from the Gulf.
The attacks, which disrupted normal life, marked return of political violence on large-scale after a gap of over a year in Kannur.
Prohibitory orders were imposed in Delhi and parts of Karnataka. Police kept tight vigil in Kerala. In Gujarat, 50 people were arrested for Thursday's violence.