Not true. Long before Hitler rose to power, the militant section of his movement, the SA, was already physically attacking political opponents. That started in the early 20's.

When he finally became head of the government, in 1933, that violence immediately became much more official: the SA was officially deputized as 'Hilfspolizei' and attacks on e.g. communists became legalized. In that same year the first concentration camps were established.