Cap-Haitien, which isn't far from Labadee, has seen a spike in violence as well. It's not just confined to the capital, but spread to basically every large city.
That said, it would be suicide for any gangs to attack tourists at Labadee, try to rob them or hold them for ransom. Given the large number of American tourists on any RC ship, any such action would very likely draw a response from the US military. I don't think the gangs are that stupid.