The FBI and Philippines police have arrested four people for allegedly hacking into AT&T’s phone systems.

The operation was carried out last week following a complaint from AT&T, after the telecom major incurred losses worth nearly $2 million due to the cyber scam, according to the Philippines police.

The investigators said the hackers worked for a group that helped finance a terrorist attack in Mumbai, India in 2008, which claimed 166 lives.

The hackers were said to be working on commission for a terrorist group linked to Muhammad Zamir a Pakistani. Following Zamir’s arrest in 2007, the group had been taken over by a Saudi national.

According to FBI spokeswoman Jenny Shearer, hackers targeted customers of AT&T, not the carrier itself.