RIO DE JANEIRO (AP) — A gunman wounded two people at a crowded bus terminal in Rio de Janeiro and took 17 others hostage aboard a bus Tuesday, and an elite police team was sent to the scene to negotiate with the assailant, Brazilian police said.

The man's motive remains unclear, Police Col. Marco Andrade said in an interview on TV news channel Globo News. “We have children and older people inside the bus,” Andrade said, adding that very little was known at this stage.

The bus was parked at the Sao Cristovao terminal in the city center and was scheduled to head to the neighboring state of Minas Gerais.

Police cars and ambulances could be seen waiting near the bus, while thousands of passengers were stranded waiting for information on scheduled travel.

People interviewed on TV said they heard several gunshots, causing panic inside the crowded terminal.

One wounded person was sent to a nearby hospital, police said.