Angular correlation spectra of $e^{+}{e}^{-}$ pairs produced in the $3H(p,e^{+}{e}^{-})4\mathrm{He}$ nuclear reaction have been studied at $E_p=510$, 610, and 900 keV proton energies. The main features of the spectra can be understood by taking into account the internal and external pair creations following the proton capture by $3H$. However, these processes cannot account for an observed peak around ${115}^{\circ }$ in the angular correlation spectra. This anomalous excess of $e^{+}{e}^{-}$ pairs can be described by the creation and subsequent decay of a light particle during the direct capture process. The derived mass of the particle is $m_X{c}^2=16.94\pm 0.12\left(\mathrm{stat}\right)\pm 0.21\left(\mathrm{syst}\right)$ MeV. According to the mass this is likely the same X17 particle, which we recently suggested [Phys. Rev. Lett. 116, 042501 (2016)] for describing the anomaly observed in the decay of $8\mathrm{Be}$.