Indian authorities are investigating whether Monday’s car blast outside Delhi’s Red Fort, which killed eight and injured at least 20, is linked to the recent arrest of seven men from Kashmir with arms and bomb-making materials.

The suspects, including two doctors, were detained in Kashmir and neighboring states during raids uncovering pistols, assault rifles, and 2,900 kg of explosive materials.

Police say the arrests revealed a “white collar terror ecosystem” involving radicalized professionals and students connected to Pakistan-based militant groups Jaish-e-Mohammad and Ansar Ghazwat-ul-Hind.

The Delhi blast is being investigated under stringent anti-terror laws, though no arrests have yet been made, Reuters has reported.

Prime Minister Narendra Modi vowed that all conspirators behind the attack would be punished.