The city's acting mayor, Oleksandr Lomako, said three explosions ripped through a busy part of the city just after 09:00 a.m. local time (0600 GMT), hitting a multi-story building.
"Unfortunately, Russia continues to engage in terrorist activity against the civilians and civilian infrastructure as confirmed by this strike on Chernihiv once again," Lomako told Ukrainian TV.
He said that several buildings, social infrastructure, and many private cars were damaged. Regional governor Vyacheslav Chaus said at least nine people were killed and more than 20 injured.
The head of Chernihiv regional hospital said at least 18 people wounded in the attack were being treated there. More injured civilians had been taken to other hospitals, he said, urging residents to donate blood.
Unverified social media videos showed flames and columns of black smoke rising over the historic city, that lies about 150 km (95 miles) from the capital Kyiv. People ran from a bus to take cover. Emergency services and medics rushed to the site of the strike, officials said.
Russia, which denies targeting civilians, invaded Ukraine in February 2022, and has launched thousands of missiles and drones on Ukrainian cities and villages in attacks that have killed hundreds of civilians.
In recent weeks Russia has intensified its attacks on Ukrainian cities, targeting the country's power sector and other critical infrastructure.
Andriy Yermak, head of President Volodymyr Zelenskiy's office, on Wednesday reiterated Kyiv's plea for more air defence.
(Reporting by Anastasiia Malenko and Olena Harmash; Editing by Ros Russell)
