Four people have been arrested after an off-duty LAPD cop was fatally ambushed by a group of armed robbers on Monday night as he was house hunting with his girlfriend. Fernando Arroyas, 27, had been on the force for three years. “He found himself, after working a series of days in patrol, to have a day off, enjoying it with his girlfriend on a hunt for a house, a place to live, a place to buy and invest in in this city and the future of this region,” LAPD Chief Michel Moore said. No further details have been released about the four suspects in custody, and it was not immediately clear what charges they might be facing. Police on Tuesday said three men and two women had been detained over the fatal encounter and were being questioned. Authorities said a black pickup truck approached Arroyas in Florence, a neighborhood in South Los Angeles, and three people got out. An argument broke out between the suspects and Arroyas before shots were fired.