  We prove a quantitative unique continuation principle for Schr\"odinger
operators $H=-\Delta+V$ on $\mathrm{L}^2(\Omega)$, where $\Omega$ is an open
subset of $\mathbb{R}^d$ and $V$ is a singular potential: $V \in
\mathrm{L}^\infty(\Omega) + \mathrm{L}^p(\Omega)$. As an application, we derive
a unique continuation principle for spectral projections of Schr\"odinger
operators with singular potentials.
