At least three people have been killed in the blast in front of a hospital in the eastern Libyan city. No group has immediately claimed responsibility.
A car laden with explosives detonated in the parking lot of the Al Jalaa hospital on Monday, hospital officials said.
The Agence France-Presse (AFP) news agency reported that four people were killed and 13 others wounded, citing a medical source.
The blast destroyed about 10 vehicles, scattering body parts of victims and shattering windows in nearby buildings, according to the Reuters news agency.
It was not immediately clear if the attack was a suicide bombing, an officer in Libya's special forces, Mohamed al-Jali, told AFP.
The Associated Press cited Mohammed Zwai, the head of the hospital's first aid unit, as saying the death toll is expected to rise, as many of those wounded are critical.
Monday's bombing was the third attack targeting the hospital this year.
Benghazi has been the scene of fighting between the Libyan National Army (LNA) led by renegade military commander Khalifa Hifter and Islamist-led opponents for more than two years. The LNA has made major advances in this year, but faces pockets of resistance in parts of the city.
Last week, Hifter's forces expelled Islamic militants from their key stronghold in the city but fighting continues in other areas.
Libya remains embroiled in violence and political chaos five years after the fall of long-time leader Muammar Gadhafi, as militias and two rival administrations vie for power and the country's oil wealth.
mm/kl (AFP, AP, Reuters)