For good and ill, Japanese emergency medical personnel have very little experience in treating weapons trauma victims.
Later - I stand corrected as to the incident in question. Two of the physicians responding to the emergency were specialists from the country's top emergency response medical corps. What time they arrived on the scene is unclear--and the NHK video did not show them treating victims--but they were there.
Even later - Well, that was instructive. I visited Japan Probe and found I was "blaming" EMS workers...for what, the link does not say.
In comments (and boy they are not fun to read!) Anonymous #1 says that the TBS broadcast claimed a full DMAT response.