Police line up shortly before the deadline for a city-wide curfew passed in Baltimore, Maryland April 28, 2015, as crowds protest the death of Freddie Gray, a 25-year-old black man who died in police custody.[Photo/Agencies]

A Chinese student found herself amid the Baltimore riots, but she was able to escape unharmed a day before thousands of police and National Guard troops fanned out to enforce a new curfew and prevent further violence in the city.

More than 3,000 police from Maryland, New Jersey and the District of Columbia, and National Guard members in helmets took up posts Tuesday in front of businesses and hospitals a day after the worst rioting in the United States in years.

Shops were looted, and buildings were burned to the ground. Twenty officers were injured, and more than 250 people were arrested in the violence that erupted following Monday's funeral of a 25-year-old black man who died in a hospital on April 19, a week after he sustained severe injuries in police custody.

The death of Freddie Gray provoked a new public outcry that flared after police killings of unarmed black men in Ferguson, Missouri and New York City last year, and in South Carolina this year.

Qian Nali, a student at John Hopkins University in the city, was driving home around 4:30 pm on Monday with a friend. Because of a roadblock and traffic jam, it took them more than an hour to go from the harbor to downtown, 50 minutes more than usual.

When they drove by Charles Street, they came across a group of 20 walking on the street arbitrarily and ignoring cars driving toward them. The cars started to make U-urns and attempt to leave the street, but the crowd started to attack the cars.

Qian saw that cars ahead of her were smashed. The crowd walked close to cars' windows. A taxi was forced to stop, and one man climbed on top of the car and began yelling loudly. A bus that was already broken down had heavy smoke coming from it.

Qian said she was terrified; they could not move or drive away. But her car was not attacked, and she drove away slowly and quietly.