The key phrase is あぶない (abunai) which is い adjective, and I assume you have learnt it as ‘dangerous‘. Translation into English will be changed depending on the tense. Let’s take a look together!
Present tense
危ない！
あぶない
abunai
watch out!
Past tense
危なかった！
あぶなかった
ABUNAKATTA
it was a close call.
Vulgar way
危ねっ
あぶねっ
Abune (‘e’ at the end is very short vowel)
IT WAS A CLOSE CALL.
