The behavior of people changes depending on whether they are in groups or alone. In the article "Individuals in Groups", Carol Tavris talks about  "diffusion of responsibility" or "social loafing". People's reactions facing dangerous situations are different depending on the number of individuals. Tavris mentions two experiments. In the first experiment, a group of students are put in a classroom facing a dangerous scenario. In the second experiment an individual went through the same experiment.

The group of individuals took longer to take themselves out of harm's way. Their reaction took longer because each individual in the group though that someone in the group was taking take of it. On the other hand the individual alone in the experiment had a faster reaction, almost immediately. I think individuals in groups would react faster, but reading the article and looking into my personal experience people in groups tend to just think some else in the group is taking care of the situation they are facing.