Science is the knowledge of how things around us function. It is akin to the knowledge that pressing a sharp knife against flesh results in a cut. It is coldly impartial, without morals and heartless. It's job is to explain how the world works and not one bit more than that. Therefore, the moral question of science causing harm or good is more a question of how the knowledge of science is applied and who applies it.
As with the analogy of the knife, it is easy to see that the knife can be a potent instrument of good when it is used by a surgeon to cut out a life threatening tumour while also being extremely evil when wielded by a goon who does not mind stabbing an innocent person for the sake of a few currency notes and credit cards. Science can be deemed as harmful when scientific knowledge is used for evil purposes, but it is important to realise that it got used evilly because the people who benefit from the use convinced the others that they were doing right. This convincing is majorly possible because not everyone thinks in a scientific way and not everyone has access to scientific information, resulting in the possibility of them being misled. It is therefore human deception of fellow humans that cause harmful uses of science and "science" by itself is not evil or harmful. Just as no one would completely ban all knives because they have some evil uses, it is unwise to label science and technology as harmful and it is more important to ensure that more people are aware and follow the scientific method of challenging and debating information that others try to put to them.
Scientific experiments and results are accurately reported in scientific publications through the mechanism of peer review, where fellow scientists have to certify a piece of work as correct before it can be published. Unfortunately, such a rigorous mechanism does not exist in the other forms of media which reach out to much larger population and therefore have more power in forming general opinion. As a result, many scientific stories can get reported erroneously or be coloured with some prejudice by the author. For instance, if an author is against the use of nuclear energy, then he/she may sometimes report even potentially beneficial advances in nuclear science with a slightly evil note, thus causing the people who read his/her column to start believing that nuclear energy is an example of harmful science. Those inclined towards science and have access to scientific publications can pursue the matter, read the concerned papers and maybe discover that the advances in fact have uses that would make it safer for use. Unfortunately, this group is not too large and it is this lack of science inclined people and lack of open access to scientific information that is most harmful.
Two major steps required to improve/correct this situation is ensuring more awareness towards science and the scientific method among the general public and providing easier access to the scientific information published in peer reviewed journals and publications. The scientific method teaches us to base our opinions on facts and evidence and not to form radical views based solely upon a few articles which have not been scrutinised by experts. It teaches us that in reporting or verifying any findings or results, our prejudices, however strong, must be placed aside and an objective report be produced. Appreciation of such a method coupled with availability of scientific information will ensure that more people understand the potential good and evil uses of any kind of science and then are able to force their governments or corporations or other groups to use them fruitfully. Not following the scientific method leaves the general public open to manipulation by the media or whoever happens to have access to the real information, a power that can be used to justify extremely counter productive actions.
It is important to realise that science is not a person or a sentient being that can harm or be harmed, it is only us who have to look out for ourselves. Even if we bomb all life on earth out of existence, all that science has taught us, like gravity, the atomic structure, the presence of electricity and magnetism, will still exist and will always do so. It is our jobs to empower ourselves by adopting the scientific technique and using it responsibly to guide our politicians into creating beneficial policies in the future. In short, it is our job to ensure that we know enough and act in a way to ensure that the knife stays in the hands of the surgeon and does not get in the hands of the goon.
Then Science will never be harmful.