seal [sth] off, seal off [sth]vtr phrasal sepphrasal verb, transitive, separable: Verb with adverb(s) or preposition(s), having special meaning, divisible--for example, "call off" [=cancel], "call the game off," "call off the game."
(isolate, cordon off)
封锁 fēng suǒ
封闭 fēng bì
The scene of the road traffic accident has been sealed off by the police.