The body of an activist from St. Louis who led protests about the fatal police shooting of Michael Brown in Ferguson, Mo., in 2014 was found with a gunshot wound in the charred remains of a vehicle on Tuesday morning, according to the police and news accounts.

The activist, Darren Seals, 29, was found inside the vehicle on Diamond Drive in Riverview in St. Louis County around 1:50 a.m., the St. Louis County Police Department said in a statement. The vehicle had been on fire and he was found after the flames were extinguished.

The police said Mr. Seals had lived at an address on Millburn Drive in St. Louis, about 12 miles from where his body was found. The case is being investigated as a homicide by the department’s Bureau of Crimes Against Persons. The motive for the killing was unknown.

The police identified Mr. Seals as Daren Seals, although other records listed the spelling of his first name as Darren, The St. Louis Post-Dispatch reported.