  We study the existence of fixed points for continuous maps $f$ from an
$n$-ball $X$ in $\mathbb R^n$ to $\mathbb R^n$ with $n\geq 1$. We show that $f$
has a fixed point if, for some absolute retract $Y\subset\partial X$,
$f(Y)\subset X$ and $\partial X-Y$ is an $(f, X)$-blockading set. For $n\geq
2$, let $D$ be an $n$-ball in $X$ and $Y$ be an $(n-1)$-ball in $\partial X$.
Relying on the result just mentioned, we show the existence of a fixed point of
$f$, if $D$ and $Y$ are well placed and behave well under $f$, and ${\rm
deg}(f_D)=-{\rm deg}(f_{\partial Y})$, where $f_D=f|D: D \rightarrow
\mathbb{R}^n$ and $f_{\partial Y}=f|\partial Y: \partial Y \rightarrow \partial
Y$. The degree ${\rm deg}(f_D)$ of $f_D$ is explicitly defined and some
elementary properties of which are investigated. These results extend the
Brouwer fixed point theorem.
