Is 'a' optional and is 'aged in his 30s' correct?

[Tan Elaine]

One man died and another is in a critical condition following a shooting in the early hours of New Year's Day.

The shooting took place in Thornton Heath, south London, at around 5am, the Met Police said.

The victim, who has not been identified, was aged in his 30s. He was taken to hospital but was pronounced dead.

Another man, aged in his 20s, is described as being in a critical condition.

1. Is 'a' needed? Or is it optional?

2. Is 'aged in his 30s' fine or should it be without 'aged' (in his 30s)?

Thanks in advance.

 

[kfredson]

One man died and another is in a critical condition following a shooting in the early hours of New Year's Day.

The shooting took place in Thornton Heath, south London, at around 5am, the Met Police said.

The victim, who has not been identified, was aged in his 30s. He was taken to hospital but was pronounced dead.

Another man, aged in his 20s, is described as being in a critical condition.

1. Is 'a' needed? Or is it optional?

2. Is 'aged in his 30s' fine or should it be without 'aged' (in his 30s).

Thanks in advance.

Drop the 'a' and the 'aged.'

"Aged" generally means either "elderly" or "changed (improved) with time," as with wine.

You can also say that someone is 21 years old or 21 years of age.

 

[Raymott]

One man died and another is in a critical condition following a shooting in the early hours of New Year's Day.

The shooting took place in Thornton Heath, south London, at around 5am, the Met Police said.

The victim, who has not been identified, was aged in his 30s. He was taken to hospital but was pronounced dead.

Another man, aged in his 20s, is described as being in a critical condition.

1. Is 'a' needed? Or is it optional?

2. Is 'aged in his 30s' fine or should it be without 'aged' (in his 30s)?

Thanks in advance.

I've never heard of a patient being "in critical condition". It must be a regional phrase. I'd always use "a".
There's also nothing wrong with "aged in his 20s". Many similar phrases can either use the participle or not:
A man in blue jeans. A man dressed in blue jeans.
A knight in shining armour. A knight clad in shining armour.

It's purely stylistic.