>>> police are dealing with a disturbing trend now. tr officers increasinglyce inunder the threat of ambush. it happened to dpd officers fi twice. one nae.rrowly escaped ebeing killed. >> reporter: when officer ronald workman arrived riat this apartment complex in north dallas, police say he drove right into an ambush. >> there is a guy walking around my apartment in a gray hoodie and he's walking around with a gun. i think he might hurt somebody. >> reporter: that 911 call came from the gunman. police say h e made the call to lure tothem in thbefore shooting the officer in the jaw. hours earlier, p olice chased a ch robbery suspect into this apartment complex. t officers say he waited to ambush police. the gunman was shot and killed. >> the officers survived both ed these situations e that could have led to much dire circumstances. >> reporter: many officers are wounded or killed in the heat of the moment. but dallas police association ce president says actually plotting to kill an officer ce happens more than we think. >> stats show that the number two situations for police deaths are ambush. >> reporter: in rnovember 2010, 2 dallas police officers responded to a family violence call. the gunman waited in a breeze way and opened fire. en one of the officers was hit several times, butse survived. s >> ambush is a problem within the profession of law enforcemw ent. it's something that's been recognized really since the alin 1990s. >> reporter:
uta c>>riminal justice profes sor randall butler is also a reserve police offilicer and says ambushes are usheually plotted by males in their 20s thor 30s with mental problems or family violence issues. >> one way of expressing their frustration is by killing a symbol of authority. >> reporter: in fact, the professor says family violence calls are more likely to lead to ambushes than any otherhe an police calls.