Emergency Code 1

From Memory Alpha, the free Star Trek reference

In the late 24th century, the term Emergency Code 1 was used aboard Federation starships in indicated an intruder alert on the bridge, that there are abductions, and injured.

In 2366, Deanna Troi alerted security of an Emergency Code-1 while Kyril Finn, and a Rutian Ansata assault force stormed the USS Enterprise-D, kidnapping Captain Picard, and shooting Lieutenant Worf. (TNG: "The High Ground")