Thank you all very much for your input and insight.

My father was a seaman on the "Kildale" so I'm relieved to learn that the casualties were most likely unintentional. He was also a crew member on the Cunard liner "Laconia" sunk six weeks earlier by U50 and had been on the "City of Liverpool" when she came under a U38 gun attack in August 1915.
Pleased to say he got through all three incidents unscathed.

Thanks again and kind regards,
Martin