Police have confirmed this morning that the body is that of a man in his 40s who is believed to live locally.
No formal identification has yet taken place and the coroner will be informed.
A police spokesman said the death is being treated as non suspicious.
The college, in Kiln Road, Thundersley was placed on lockdown after firefighters discovered a body inside a car which was ablaze on the campus forecourt.
The car is thought to have arrived in the car park at around 4:55pm before bursting into flames moments later.
More than ten police cars rushed to the scene and cordoned off the area while emergency services conducted an investigation into the cause of the incident.
Pc Gavin Freeman said at the scene: “The fire brigade contacted us shortly after 5pm after a body was discovered in a car which was on fire. We have been unable to provide a positive identification at this time, neither can we say whether it is a man or a woman as the body is too badly damaged.
“Anyone with information is asked to contact Southend CID on 101.”
Seevic College principal Nick Spenceley issued a statement last night
He said: "A car arrived at the College car park in Runnymede Chase at 4.55pm this evening, after all lessons at the college had finished for the day.
"The car caught fire shortly afterwards, and we are awaiting further details from the police at this time."
Shocked students and residents in the area have been reacting to the news on Twitter.
Danny Allott tweeted: "Shocking news about the car explosion at Seevic."
Kellly Cornwell said: "Actually in shock at what's happened at Seevic. RIP to the body found in the car."
Jodi O'Sullivan added: "RIP to whoever was in that car at Seevic, absolutely devastating."
Earlier, a number of police cars and ambulances were called to the scene and cordoned off the area.
Emma Hart on Twitter said: "Can't believe I saw someone's car explode at Seevic."