According to an example aspect of the present invention, there is provided a method comprising determining that a first mobile terminal is a personal device, receiving, from the first mobile terminal, information about a status of the first mobile terminal, determining whether the first mobile terminal is a Vulnerable Road User, VRU, with respect to a vehicle based at least partly on the received information about the status of the first mobile terminal, detecting a potential collision between the first mobile terminal and the vehicle when the first mobile terminal is determined as a VRU and transmitting at least one warning message to the first mobile terminal in case that the first mobile terminal is determined as a VRU and the potential collision is detected.