In 2084, Sea Base 4 was involved in a conflict with the Sea Devils and the Silurians. The Sea Devils and Silurians were killed by hexachromite gas released by the Fifth Doctor. As Turlough explained, "They're all dead, you know." (TV: Warriors of the Deep)
Behind the scenes Edit
In the novelisation of Warriors of the Deep, it was mentioned there were several human survivors, including Bulic, scattered around the base.