(CNN) -- About an hour and a half into his trip from the Tunisian border to Tripoli on Saturday, CNN photojournalist Craig Johnston sensed something was about to change.
"The two government drivers -- they wouldn't say much to us," said Johnston, who was in a bus ferrying fellow journalists from Sky News and Reuters from Djerba to the Libyan capital. "It was a little bit tense."
Johnston said he began to notice armed men massing along the road, and large amounts of civilian traffic traveling in the opposite direction.
"I could sense the tension was getting worse," he said.
Ten minutes later, the bus drove directly into a firefight outside the coastal city of al-Zawiya.
Rebels said Saturday that they had entered the key coastal city 33 miles west of Tripoli, with some claiming they are now in control of up to 85% of it. The government strongly denied those claims.
The drivers of the bus tried to flee the fighting as soldiers ran down the road, yelling, "Go, go, go!"
But they were hemmed in by civilian traffic.
Eventually, after a series of turns amid the gunfire, the bus drivers maneuvered away from the danger.
The situation lasted about 20 minutes.
Once safely away from the fighting, they stopped to regroup, with one of the drivers going to pray at a mosque. As they left the scene, black smoke rose from points along the road. It was unclear whether it was the result of NATO airstrikes or continued fighting in the area.
The group was back in Djerba on Saturday night after being told to leave Libya.