aynı anda, hep birden

listen to the pronunciation of aynı anda, hep birden
Turkish - English
all at once
Unexpectedly; without warning; all of a sudden

When all at once I saw a crowd, A host, of golden daffodils - William Wordsworth, Daffodils.

without warning; "all at once, he started shouting"
suddenly, at one time, simultaneously
all at the same time; "Let's say `Yes!' all at once"