A suspected small-scale homemade bomb exploded at a general hospital in Hong Kong on Monday, causing the temporary evacuation of some patients but no injuries, police said.

The incident came after a group of protesters on Sunday set alight the lobby of a newly built residential building in Hong Kong that authorities had planned to use as a quarantine facility, as fears grow over a coronavirus outbreak in mainland China.

Hong Kong has been convulsed with demonstrations over the past seven months centered on its relationship with mainland China, with anger fueled by what protesters see as growing interference from Beijing.

The device exploded in a toilet cubicle at the Caritas Medical Center at about 2.30 a.m. local time, police said in a statement.

The explosive ordnance disposal unit “found a suspicious bomb inside a toilet, 15 centimeters long, 10 centimeters in diameter,” police said.

“They took away the pieces of the suspicious bomb for further examination and evacuated around 20 people to a safe place. No one was injured. “

The motive for the hospital explosion was not known.

There have been calls by pro-democracy legislators, activists and a medical staff union in recent days for Hong Kong to shut the border with the mainland to prevent the coronavirus from spreading.

Hong Kong on Sunday barred residents of China’s Hubei province, the center of the virus outbreak, from entering the city. Chief Executive Carrie Lam last week dismissed a border closure as inappropriate and impractical.

Hong Kong has so far confirmed eight cases of people infected with the virus, which has killed 80 people in mainland China.

RELATED PHOTOS Riot police wear protective masks while standing guard on Nathan Street in the Mong Kok district of Hong Kong on Sunday. | BLOOMBERG