The news came as US President Joe Biden was visiting the Polish capital Warsaw and preparing to make a major speech on Russia's war against Ukraine.
According to unconfirmed information, a fuel depot and a military site were targeted in the area, Poland's PAP news agency reported.
An official from the Lviv city council was quoted as saying that there were "three powerful explosions" near the city.
"There have been three powerful explosions near Lviv ... Everyone should keep calm and stay indoors," Igor
Zinkevych said in a post on Facebook, as quoted by the Reuters news agency.
Witnesses saw heavy black smoke rising from the north-east side of the city, Reuters reported.
Lviv, a city in western Ukraine near the Polish border, is where hundreds of thousands civilians have found refuge far from war's main battlefields.
Earlier this month, Russian troops fired missiles at an airport near the city.
Black smoke rises into the sky from around Lviv airport in western Ukraine on March 18, 2022. Photo: PAP/Newscom
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Source: IAR, PAP, Reuters