A compressive imaging system and method for quickly detecting spectrally and spatially localized events (such as explosions or gun discharges) occurring within the field of view. An incident light stream is modulated with a temporal sequence of spatial patterns. The wavelength components in the modulated light stream are spatially separated, e.g., using a diffractive element. An array of photodetectors is used to convert subsets of the wavelength components into respective signals. An image representing the field of view may be reconstructed based on samples from some or all the signals. A selected subset of the signals are monitored to detect event occurrences, e.g., by detecting sudden changes in intensity. When the event is detected, sample data from the selected subset of signals may be analyzed to determine the event location within the field of view. The event location may be highlighted in an image being generated by the imaging system.