Fuel leaked on the Trakia motorway after a lorry crashed at the 157km mark on the Sofia-bound carriageway, the regional Interior Ministry directorate said. For now, traffic is moving only in the fast lane.
Police got the call minutes before 5pm. Early reports say the lorry left the road and no other vehicle was involved.
The driver, 56, was taken to hospital. Early reports say he felt unwell. An alcohol test at the scene was negative.
A police team is working at the site.