Force India was involved in a Molotov cocktail attack earlier this week, resulting in two team members returning to the UK and Nico Hulkenberg and Paul di Resta sitting out the second practice session on Friday.
Now, the Swiss team Sauber has revealed it saw masked protesters throwing petrol bombs whilst returning from the circuit to their Manama hotel late on Thursday.
"At 20.50 the 12 mechanics, being on that minibus to the Novotel, noticed fire on the medial strip of the highway," said spokesman Hanspeter Brack.
"On the opposite lane there was no traffic. The team members saw a few masked people running from there over to their lane where a bottle was burning as well."
No one was hurt.
F1 chief executive Bernie Ecclestone on Friday played down the latest drama, accusing reporters of "wanting a story" and offering to ride in the cars with the frightened Force India team members if they are afraid of Bahrain's night.