Lewis Hamilton said members of his Mercedes team had guns held to their heads as they were robbed as they left the Interlagos circuit on Friday.
"Some of my team were held up at gun point last night leaving the circuit here in Brazil. Gun shots fired, gun held at ones head. This is so upsetting to hear," world champion Hamilton tweeted.
"Please say a prayer for my guys who are here as professionals today even if shaken."
A Mercedes spokesman said: "We can confirm that a team minibus was robbed at gunpoint last night leaving the circuit. Valuables were stolen, but most importantly everybody is safe and uninjured."
Some of my team were held up at gun point last night leaving the circuit here in Brazil. Gun shots fired, gun held at ones head. This is so upsetting to hear. Please say a prayer for my guys who are here as professionals today even if shaken.
Members of the Williams team and officials of the FIA, motor sports' governing body, were also targeted by robbers, the BBC's chief Formula One writer Andrew Benson tweeted early Saturday.
"Some Mercedes personnel were robbed at gunpoint leaving the track last night. No-one harmed. Close escapes for FIA and Williams people, too." Benson wrote.
Hold-ups are a known risk for teams in Sao Paulo and around the Interlagos circuit, with drivers travelling to and from their hotels with police escorts and in cars with bulletproof protection.
Briton Jenson Button was the victim of an attempted armed robbery in 2010.
"This happens every single year here. F1 and the teams need to do more, there’s no excuse!” Hamilton Tweeted.
This happens every single year here. F1 and the teams need to do more, there’s no excuse!
The robbery is not the first to involve Mercedes in Latin America at an F1 event. A team member was ambushed in similar circumstances in 2016 at the Mexican Grand Prix.
This incident comes at a time when the Brazilian Grand Prix and Brazilian motor sport faces an uncertain future.
The Interlagos track is up for sale. The city of Sao Paulo said late Friday that it is in discussions with three possible purchasers of the track and had made it a condition of sale that the new owners guarantee retaining the Brazilian Grand Prix beyond 2020, when the current contract ends.