There was no gunfire early Tuesday as troops search an Indian air base on the fourth day of a siege looking for a possible sixth gunman involved in a weekend attack that left seven troops dead.

Indian security forces killed a fifth gunman on Monday at the base near the border with Pakistan.

The search operations at Pathankot air force base will continue until all areas have been completely secured, Maj. Gen. Dushyant Singh, from India's National Security Guard, told reporters. The attack has dragged on since early Saturday morning as troops struggle to find the heavily armed attackers in the sprawling base. At least twice it has appeared that the attack had ended but fresh gunfire and explosions erupted both times.