Dallas Mayor does not rule out terrorism?

I just watched the interview with the Dallas Mayor and he says he can't rule out terrorism.  Additionally he says that the suspects are not cooperating and that they're trying to find out who's behind them.

Could we be looking at a major terrorist event?

These guys were prepped.  They were too well prepared for this to have been pulled together in the days since we saw the police shootings that sparked the protests.

Additionally we don't know how these guys were equipped.  There might be alot more to this than any of us suspect.