  We study the probability distribution $P(X_N=X,N)$ of the total displacement
$X_N$ of an $N$-step run and tumble particle on a line, in presence of a
constant nonzero drive $E$. While the central limit theorem predicts a standard
Gaussian form for $P(X,N)$ near its peak, we show that for large positive and
negative $X$, the distribution exhibits anomalous large deviation forms. For
large positive $X$, the associated rate function is nonanalytic at a critical
value of the scaled distance from the peak where its first derivative is
discontinuous. This signals a first-order dynamical phase transition from a
homogeneous `fluid' phase to a `condensed' phase that is dominated by a single
large run. A similar first-order transition occurs for negative large
fluctuations as well. Numerical simulations are in excellent agreement with our
analytical predictions.
