RELATED: Visalia man accused of plotting to kill 3 Bay Area doctors
"As soon as Visalia Police contacted us we viewed this threat as real and credible," said Lt. James Reifschneider with Palo Alto Police Department.
Chen's wife contacted Visalia Police after Chen took off in a rental car last week with two registered firearms leaving a note behind that said, "If today I do not kill them, their sins will continue."
CHP Officers stopped Chen on Southbound 101.
"As many stops as we make we don't know where our interdiction may have stopped a crime or saved a life in this situation we knew," said CHP Officer Ross Lee.
In Chen's rental car, they discovered a notebook with the names and home addresses of doctors, a face mask and 2 handguns registered to him.
"They did have extended capacity magazines which were illegal, the guns were loaded, one of those guns had 30 rounds of ammunition in it, the other had 16 rounds of ammunition and as I say they were within arms reach of him," said Lt. Reifschneider.
Investigators also recovered a note titled "Why do I Kill" with the reasons "revenge" and "this is the possible result if you treat people as an animal."
Chen is being held at Santa Clara County Main Jail on 3 counts of attempted murder.
While the complaint names the three doctors, the Santa Clara County District Attorney's Office asked ABC7 News not to release their names out of safety concerns. Palo Alto Police say they believe more than 3 doctors were potentially at risk last week.
If you have any information on this case, you are asked to contact the Palo Alto Police Department at Chen (650) 329-2413 or send an anonymous tip to firstname.lastname@example.org or (650) 383-8984.