American photojournalist Bing Guan spoke with CNN's Becky Anderson on Monday regarding the escalated tension with Hong Kong university protesters.

In the interview, Bing stated that "clashes last night were heaviest seen so far."

Guan went on to describe the chaotic scene.

"SWAT vehicles rushed line of protesters who were holding onto umbrellas and barricades," he said. "Makeshift barricades with chairs were used as defense from authorities."

Guan noted that the Hong Kong police are "unpredictable" and there is a lot of uncertainty at the moment. He said Hong Kong is preparing for the worst.