The event occurred in Amira Kadal, a busy commercial hub that sees a large influx of shoppers.
Harjot Singh is one of the 200 stranded Indians being repatriated from Poland, which shares a border with Ukraine.
While the Shiv Sena gave no formal reason for Thackeray's absence, party leaders said the chief minister wants to send a strong message to Prime Minister Modi about the Centre's alleged persecution of Sena and MVA leaders.