They were alarmed by a sudden attack.

突然袭击使他们大为惊恐。

youdao

I had a sudden attack of acute myocardial infarction at home and had first-aid treatment for about 3 hours at the spot prior to admission.

我在家里突然发生急性心肌梗死，入院前在现场抢救了3个小时。

youdao

Network traffic anomaly refers to the status that traffic behaviors depart from the normal behaviors, which has characteristics of a sudden attack and the unknown threatened characteristics.

网络流量异常是指网络的流量行为偏离其正常行为的情形，具有发作突然、先兆特征未知的特点，有可能在短时间内给网络及其设备带来极大的伤害。

youdao

A seizure is a sudden attack that may affect a person's mind or body for a short period.

VOA: special.2010.10.26

The Intensive Care Unit (ICU) where sickle cell patients go for treatment when suffering a sudden attack lost all five of its consultants and one of them is still in jail.

BBC: Bahrain sickle cell death rise causes concern

In 1970, both men died, the salesman, of a sudden heart attack on a tennis court, and the professor, of cancer.

FORBES: The Spaceship Takes Off From Cupertino

He died Wednesday of a sudden heart attack.

FORBES: RIP Microsoft ClearType Inventor Bill Hill