All of U.S.1 along the 18-Mile Stretch in the Florida Keys was closed Tuesday evening due to a wildfire. (Video courtesy: Monroe County Sheriff’s Office)

MIAMI — A stubborn wildfire has once again shut down Florida’s 18-Mile Stretch highway that is the primary link to the Florida Keys, severing a crucial travel artery Wednesday afternoon.

Both the 18-Mile Stretch along US 1 and Card Sound Road are currently blocked in both directions as fire crews work to mitigate a brush fire burning in southern Miami-Dade County area, according to the Monroe County Sheriff’s Office.

The highway was shut down for hours Tuesday afternoon and evening as smoke and nearly flames dropped visibilities to dangerously low levels. The road was eventually reopened around 8:30 p.m. Tuesday before shutting down again around 4 p.m. Wednesday.

The blaze has burned about 4,000 acres and is just 20% contained, according to the Florida Forestry Service.

This is a breaking news story. Updates to follow soon.