The suspect in an attack on the ruling Liberal Democratic Party’s headquarters and the Prime Minister’s Office over the weekend was sent to prosecutors on Sunday, as more details emerged about the incident, although the suspect’s motive remained unclear.

The suspect, who media reports identified as 49-year-old Atsunobu Usuda from Kawaguchi, Saitama Prefecture, was arrested early Saturday in Tokyo, after he threw what appeared to be multiple Molotov cocktails at the LDP’s headquarters before ramming a car into a security fence outside the Prime Minister's Office.

In response to the attack, security measures have been strengthened outside both sites as police look to prevent further incidents in the run-up to the Oct. 27 Lower House election.