A protester holds a sign as clouds of smoke and crowd control agents rise, shortly after the deadline for a city-wide curfew passed in Baltimore, Maryland April 28, 2015.[Photo/Agencies]

Sun, who declined to give her full name, is a Chinese freelancer who lives with her husband about a 10-minute drive from where the riots occurred. The TV news and the Baltimore police Twitter account are her sources for riot news every few minutes.

Sun, who has lived in the US for more than three years, said on Tuesday that she hadn't been outside.

"I'll be careful to stay indoors," she told China Daily. "I talked with my neighbors yesterday, and they've got their guns prepared at home."

"We still have some food bought (from) last week, but not too much," she said. "When we are run out of food, probably we'll try to go to the supermarket … away from the riots."

Yang Lishi, a visiting scholar at the University of Maryland, Baltimore, who has been in the US less than two months, said that the traffic on the daily route she walks though seemed thinner. Her classes were canceled, and she has been receiving safety-warning e-mails from the university since Saturday.

"I haven't seen the riots, but my colleague said there were demonstrations on her way back home, and some protesters even patted against her car windows," Yang said. "Even though the campus looks normal as usual, we're scared."

Messages from riot witnesses like Qian were sent over Chinese social media site WeChat, which has 70 million users outside of China, according to Tencent.