The National Investigation Agency on Thursday raided 10 Delhi locations including Shaheen Bagh in connection with the April 2 train arson in Kerala in which a man set fire to his co-passengers.

The main accused, Shaheen Bagh resident Shahrukh Saifi, has already been arrested. Thursday’s raids were aimed at arresting other suspects, said a source in the NIA, which has taken the investigation over from Kerala police following a Union home ministry order and invoked the anti-terror law UAPA.

“We suspect that he (Saifi) was sent to Kerala by his handlers to carry out the attack. We are conducting raids to arrest Saifi’s handlers and aides who may have been part of the conspiracy,” an NIA official said in the evening while the raids were continuing.

He would not reveal whether any arrests had been made.

On April 2 night, Saifi allegedly set fire to co-passengers on the Alappuzha-Kannur Executive Express near Elathur in Kozhikode. Nine people suffered burns while three, including a toddler, were found dead on the tracks. The police suspect that they fell while trying to escape the fire.

Saifi, who suffered injuries in the attack, faces murder and terror charges.