But it could be any kind of theft in this scenario, not just petty theft. It could even have been a random kid with undeveloped morals and an opportunity to seize a toy for free. Even wealthy neighborhoods are not safe from this; gangs are not necessary to explain the situation here, let alone allusions to rape or murder.

With that said, yes, reporting it to the nearest police station is still a sensible idea regardless of context.

its petty theft because of the value of the bike. Theft is classified in the value of stolen goods, if it was moped instead, it would be grand theft