more than one attempt at slaughtering an animal

[Talib84]

Assalamu Alaikum

Someone says Bismilahi Allahu Akbar and cuts the throat of an animal and some blood starts squirting out. Someone else says the animal has not been slaughtered yet, so the person cuts again and the blood starts gushing out. Is the slaughter valid?

Jazak Allah

[Mulla]

The second time you cut, you must say Bismillah Allahuakbar